For example, instead of going to Settings > General > Accessibility > Reachability, you can just search for Reachability.
|
|
Reachability on iOSScreenshot: GizmodoAndroid doesn't have an official mode like Reachability built into it, but some Android manufacturers have added one anyway.
|
|
Enable Reachability modeApple introduced a feature called Reachability into iOS back in 2014, and it's been helping users hit menus and icons at the top of the screen ever since.
|
|
No need for reachability, no need for adjusting your hands.
|
|
It's impossible to use one-handed — even with reachability enabled.
|
|
Which is why I am so glad that reachability still exists.
|
|
You know, the idea of it was that idea of reachability.
|
|
Here's how: Open Settings>General>Accessibility Make sure "Reachability" is turned on.
|
|
Good thing you can make it easier to call up with Reachability.
|
|
There were even rumors that the company was planning to eliminate the "reachability" feature entirely, which would likely have made the 5.8-inch screen a hard sell for everyone who grew accustomed to the reachability in previous generations of iPhones.
|
|
It took me a little longer to figure out how to consistently use Reachability.
|
|
Reachability is now tucked away in Accessibility, if you're reading this and looking for it.
|
|
On earlier, Plus-sized iPhones, Reachability was easy to trigger with the physical home button.
|
|
I still suck at Reachability, and find the double home button tap on older iPhones much easier.
|
|
The increase in vertical size is lovely for reading and viewing movies, but it's hell on reachability.
|
|
It is much easier to use Reachability with other iPhones: you just tap the home button twice.
|
|
The keyboard will then shrink down and shift to the left and right side for easier thumb reachability.
|
|
How "reachability" works: Opportunities to target users increase the more time a user spends time on the platform.
|
|
Lauryn also said more people need to focus on the overall reachability of a podcast across the world.
|
|
Google's Gboard smushed the keyboard to one side and Microsoft's Word Flow curved the keyboard into an arc for better reachability.
|
|
Federighi reminded us that the "reachability" option under accessibility still exists, and it does move Control Center access halfway down the screen.
|
|
And while the iPhone X isn't as big as the iPhone 7 or 8 Plus, Apple has still made "reachability" an accessible feature.
|
|
Now there is no home button, so the new way to trigger Reachability is to swipe down from the bottom of the screen.
|
|
Apple said the Reachability swipe gesture was designed as a quick action to let people easily reach for the top of the screen.
|
|
Reachability on the iPhone X is slightly different without the home button — and it might be even easier to use than it was before.
|
|
To use it, first you must go to your Settings, head to General, find Accessibility, see Reachability and swipe right to turn it on.
|
|
On past iPhones, Reachability let people tap the home button twice to lower the top of the screen and reach for the buttons up there.
|
|
Actually, lots of people asked about Reachability, which is the iOS feature that brings the top of the screen down to make one handed usage easier.
|
|
But Reachability (a setting that pushes the top of the screen down to make it more accessible to your thumb) is tough to get used to.
|
|
Given that Apple continues to employ its Reachability feature on the bigger phone, it's possible that it will continue to receive improvements over the coming years.
|
|
Also for Android and also in an early beta form is Reachability Cursor, which is free in its basic form but has the option of a premium version.
|
|
To compensate, the company introduced Reachability—a quick double tap of the home button that shifts the screen's apps downward two inches, into the range of tiny hands.
|
|
It doesn't stop there either: screenshots, reachability (the feature that makes larger iPhone displays easier to navigate), and — of course — exiting apps will all be drastically different now.
|
|
Why it matters: "Reachability" or in technical advertising terms, "addressability," is crucial to advertisers because it reflects the number of users active enough to be reached by ads.
|
|
India's Paytm app, which recently reported more transactions on its platform than all plastic cards combined in the country, has found a way to further bolster its reachability.
|
|
You can use Apple's reachability feature to pull down the UI and then swipe, but that's two swipes for one thing, and it just makes me a little sad.
|
|
Now, when you activate Reachability (swipe down on the gesture bar), the entire screen will slide down and you can swipe down right above the upper right app icons.
|
|
One flaw frustrated me in both iPhones: the poor design of Reachability, the software feature that was designed to make larger phone screens easier to use with one hand.
|
|
One UI 2 includes more glanceable information, better reachability for one-handed use, and "more vibrant hues" throughout the OS. Animated icons will be available too, and a full dark mode.
|
|
Reachability on the iPhone X requires a precise pull-down on the bar at the bottom of the home screen, and a slightly-off swipe opens up Spotlight search instead. Yup.
|
|
There is a clear opportunity here for Apple to use the iPhone's pressure sensitivity, called 3D Touch, to let you press hard on the bottom of the screen to trigger Reachability.
|
|
Designed to improve reachability – something that's often an issue on larger-screened phones – the keyboard is activated by either left-swiping or right-swiping from the edges of the standard iOS keyboard.
|
|
For example, it rolled out a Reachability feature with the iPhone 6 Plus that allows you to lightly double tap on the Home button to pull the screen down, so you reach the icons at the top of the screen with your thumb.
|
|
Whereas most phones with rear-positioned fingerprint sensors place them in the center and below the camera (as seen on the LG G6, which is the lower phone in the image above) for better index finger reachability, the S8 seems to place it much higher.
|
|
When Apple's screen sizes started growing with the iPhone 25 in 26, the company released a software shortcut, called Reachability, through which users can tap the home button twice to lower the top of the screen and make it easier to reach buttons up there.
|
|
Opera Touch on iOSScreenshot: GizmodoIf you're on Android, you can take advantage of the experimental One-Handed Mode app from XDA Developers, which attempts to duplicate the functions of Reachability in iOS by shrinking down the screen so it's easier to get at with one hand.
|
|
Screenshot: GizmodoIt's one of the most intuitive and simple ways of managing controls on a larger screen that we've seen to date, and it even feels easier to use than Reachability on iOS (which will put menus and settings directly under your thumb after a specific swipe).
|
|
It's disabled by default in iOS 12, but can be switched on by tapping General then Accessibility in Settings and toggling the Reachability switch to On.With that done, a short swipe down or a quick swipe up and down near the bottom of the display brings the top half of the screen down so you can get to it more easily with one hand.
|
|
Most users still find it simpler to navigate the iPhone with a fingerprint sensor and home button, but you have to go back in time to get those things, since the new models rely on navigation gestures and Face ID. The iPhone 22020 makes some kinds of multitasking easier, and the phone is actually usable with one hand thanks to a smaller screen and Reachability features.
|
|
You "click" it to go home (the original functionality), or to unlock the phone with Touch ID. You press and hold to talk to Siri, double tap (not click) to make the screen slide down for thumb reachability, double click (not tap) when the phone is locked to pull up Apple Pay, long tap to pay with Apple Pay, double click to pull up the app switcher when the phone is unlocked, and probably a few other things I'm forgetting.
|
|
Maria: The Modular Reachability Analyzer is a reachability analyzer for concurrent systems that uses Algebraic System Nets (a high-level variant of Petri nets) as its modelling formalism.
|
|
Note that it is not the average reachability of the neighbors from A (which by definition would be the ), but the distance at which A can be "reached" from its neighbors. With duplicate points, this value can become infinite. The local reachability densities are then compared with those of the neighbors using which is the average local reachability density of the neighbors divided by the object's own local reachability density. A value of approximately indicates that the object is comparable to its neighbors (and thus not an outlier).
|
|
Previous linear-time algorithms are based on depth-first search which is generally considered hard to parallelize. Fleischer et al. in 2000 proposed a divide-and-conquer approach based on reachability queries, and such algorithms are usually called reachability-based SCC algorithms. The idea of this approach is to pick a random pivot vertex and apply forward and backward reachability queries from this vertex.
|
|
Reachability is a fundamental problem that appears in several different contexts: finite- and infinite-state concurrent systems, computational models like cellular automata and Petri nets, program analysis, discrete and continuous systems, time critical systems, hybrid systems, rewriting systems, probabilistic and parametric systems, and open systems modelled as games.Giorgio Delzanno, Igor Potapov (Eds.): Reachability Problems - 5th International Workshop, RP 2011, Genoa, Italy, September 28–30, 2011. Proceedings. Lecture Notes in Computer Science 6945, Springer 2011, In general the reachability problem can be formulated as follows: : Given a computational (potentially infinite state) system with a set of allowed rules or transformations, decide whether a certain state of a system is reachable from a given initial state of the system. Variants of the reachability problem may result from additional constraints on the initial or final states, specific requirement for reachability paths as well as for iterative reachability or changing the questions into analysis of winning strategies in infinite games or unavoidability of some dynamics.
|
|
It has an edge whenever can reach . That is, it has an edge for every related pair of distinct elements in the reachability relation of , and may therefore be thought of as a direct translation of the reachability relation into graph-theoretic terms. The same method of translating partial orders into DAGs works more generally: for every finite partially ordered set , the graph that has a vertex for each member of and an edge for each pair of elements related by is automatically a transitively closed DAG, and has as its reachability relation. In this way, every finite partially ordered set can be represented as the reachability relation of a DAG.
|
|
A practical issue of reachability analysis is the so-called ″state space explosion″. If the two entities of a protocol have 100 states each, and the medium may include 10 types of messages, up to two in each direction, then the number of global states in the reachability graph is bound by the number 100 x 100 x (10 x 10) x (10 x 10) which is 100 million. Therefore a number of tools have been developed to automatically perform reachability analysis and model checking on the reachability graph. We mention only two examples: The SPIN model checker and a toolbox for the construction and analysis of distributed processes.
|
|
Reachability analysis is a solution to the reachability problem in the particular context of distributed systems. It is used to determine which global states can be reached by a distributed system which consists of a certain number of local entities that communicated by the exchange of messages.
|
|
Objects B and C have the same reachability distance (), while is not a k nearest neighbor This distance is used to define what is called reachability distance: In words, the reachability distance of an object A from B is the true distance of the two objects, but at least the of B. Objects that belong to the k nearest neighbors of B (the "core" of B, see DBSCAN cluster analysis) are considered to be equally distant. The reason for this distance is to get . Note that this is not a distance in the mathematical definition, since it is not symmetric. (While it is a common mistake to always use the , this yields a slightly different method, referred to as Simplified-LOF) The local reachability density of an object A is defined by which is the inverse of the average reachability distance of the object A from its neighbors.
|
|
Furthermore, the queries then can be batched in a prefix- doubling manner (i.e. 1, 2, 4, 8 queries) and run simultaneously in one round. The overall span of this algorithm is log2 n reachability queries, which is probably the optimal parallelism that can be achieved using the reachability- based approach.
|
|
In discrete mathematics and theoretical computer science, reconfiguration problems are computational problems involving reachability or connectivity of state spaces.
|
|
The controllability of systems with input and state constraints is studied in the context of reachability and viability theory.
|
|
The reachability relationship in any directed acyclic graph can be formalized as a partial order on the vertices of the DAG. In this partial order, two vertices and are ordered as exactly when there exists a directed path from to in the DAG; that is, when is reachable from .. However, different DAGs may give rise to the same reachability relation and the same partial order.. For example, the DAG with two edges and has the same reachability relation as the graph with three edges , , and . Both of these DAGS produce the same partial order, in which the vertices are ordered as . If is a DAG, its transitive closure is the graph with the most edges that represents the same reachability relation.
|
|
A related problem is to solve reachability queries with some number k of vertex failures. For example: "Can vertex u still reach vertex v even though vertices s_1, s_2, ..., s_k have failed and can no longer be used?" A similar problem may consider edge failures rather than vertex failures, or a mix of the two. The breadth-first search technique works just as well on such queries, but constructing an efficient oracle is more challenging... Another problem related to reachability queries is in quickly recalculating changes to reachability relationships when some portion of the graph is changed.
|
|
The reachability graph of stochastic Petri nets can be mapped directly to a Markov process. It satisfies the Markov property, since its states depend only on the current marking. Each state in the reachability graph is mapped to a state in the Markov process, and the firing of a transition with firing rate λ corresponds to a Markov state transition with probability λ.
|
|
These are considered to be outliers. The local density is estimated by the typical distance at which a point can be "reached" from its neighbors. The definition of "reachability distance" used in LOF is an additional measure to produce more stable results within clusters. The "reachability distance" used by LOF has some subtle details that are often found incorrect in secondary sources, e.g.
|
|
The reachability problem for Petri nets was known to be -hard for a long time, but shown to be non-elementary, so it is provably not in .
|
|
In graph theory, reachability refers to the ability to get from one vertex to another within a graph. A vertex s can reach a vertex t (and t is reachable from s) if there exists a sequence of adjacent vertices (i.e. a path) which starts with s and ends with t. In an undirected graph, reachability between all pairs of vertices can be determined by identifying the connected components of the graph.
|
|
The computational law of reachable optimality has four key components as described below. 1\. Reachability of Optimality: Any intended optimality shall be reachable. Unreachable optimality has no meaning for a member in the ordered system and even for the ordered system itself. 2\. Prevailing and Consistency: Maximizing reachability to explore best available optimality is the prevailing computation logic for all members in the ordered system and is accommodated by the ordered system. 3\.
|
|
The Java package `java.lang.ref` supports soft, weak and phantom references, resulting in the additional object reachability states softly reachable' and phantom reachable. Unreachable memory is often associated with software aging.
|
|
Any pair of vertices in such a graph can reach each other if and only if they belong to the same connected component; therefore, in such a graph, reachability is symmetric (s reaches t iff t reaches s). The connected components of an undirected graph can be identified in linear time. The remainder of this article focuses on the more difficult problem of determining pairwise reachability in a directed graph (which, incidentally, need not be symmetric).
|
|
The property of non-negative rational-valued lifespans which can be preserved or changed by input events along with finite numbers of states and events guarantees that the behavior of FD-DEVS networks can be abstracted as an equivalent finite- vertex reachability graph by abstracting the infinitely-many values of the elapsed times using the time abstracting technique introduced by Prof. D. Dill [Dill89]. An algorithm generating a finite-vertex reachability graph (RG)has been introduced in [HZ06a], [HZ07].
|
|
Algorithms for determining reachability fall into two classes: those that require preprocessing and those that do not. If you have only one (or a few) queries to make, it may be more efficient to forgo the use of more complex data structures and compute the reachability of the desired pair directly. This can be accomplished in linear time using algorithms such as breadth first search or iterative deepening depth-first search.. If you will be making many queries, then a more sophisticated method may be used; the exact choice of method depends on the nature of the graph being analysed. In exchange for preprocessing time and some extra storage space, we can create a data structure which can then answer reachability queries on any pair of vertices in as low as O(1) time.
|
|
Typically, for a fixed system description given in some form (reduction rules, systems of equations, logical formulas, etc.) a reachability problem consists of checking whether a given set of target states can be reached starting from a fixed set of initial states. The set of target states can be represented explicitly or via some implicit representation (e.g., a system of equations, a set of minimal elements with respect to some ordering on the states). Sophisticated quantitative and qualitative properties can often be reduced to basic reachability questions.
|
|
In the simplest case, the medium between two entities is modeled by two FIFO queues in opposite directions, which contain the messages in transit (that are sent, but not yet consumed). Reachability analysis considers the possible behavior of the distributed system by analyzing all possible sequences of state transitions of the entities, and the corresponding global states reached Note: The corruption or loss of a message is modeled as a state transition of the medium. . The result of reachability analysis is a global state transition graph (also called reachability graph) which shows all global states of the distributed system that are reachable from the initial global state, and all possible sequences of send, consume and service interactions performed by the local entities. However, in many cases this transition graph is unbounded and can not be explored completely.
|
|
First, each node needs to determine what other ports it is connected to, over fully working links; it does this using a reachability protocol which it runs periodically and separately with each of its directly connected neighbours.
|
|
The transitive reduction of a DAG is the graph with the fewest edges that represents the same reachability relation as . It is a subgraph of , formed by discarding the edges for which also contains a longer path connecting the same two vertices. Like the transitive closure, the transitive reduction is uniquely defined for DAGs. In contrast, for a directed graph that is not acyclic, there can be more than one minimal subgraph with the same reachability relation.. A Hasse diagram representing the partial order of set inclusion (⊆) among the subsets of a three-element set.
|
|
Given the expressiveness of hybrid automata it is not surprising that simple reachability questions are undecidable for general hybrid automata. In fact, a straightforward reduction from Counter machine to three variables hybrid automata (two variables for storing counter values and one to restrict spending a unit-time per location) proves the undecidablity of the reachability problem for hybrid automata. A sub-class of hybrid automata are timed automata Alur, R. and Dill, D. L. "A Theory of Timed Automata". Theoretical Computer Science (TCS), 126(2), pages 183-235, 1995.
|
|
The SPB Link Metric sub-TLV occurs within the Multi-Topology Intermediate System Neighbor TLV or within the Extended IS Reachability TLV. Where this sub-TLV is not present for an IS-IS adjacency, then that adjacency will not carry SPB traffic for the given topology instance. There are multiple ECT algorithms defined for SPB; however, for the future, additional algorithms may be defined; similarly the SPB Adjacency Opaque Equal Cost Tree Algorithm TLV also occurs within the Multi-Topology Intermediate System TLV or the Extended IS Reachability TLV.
|
|
Example of Presence Information The term presentity is a combination of two words - "presence" and "entity". It basically refers to an entity that has presence information associated with it; information such as status, reachability, and willingness to communicate.
|
|
Target set, states and strata in CST Concept of Stratification, labelled CST by Prof Lotfi A. Zadeh, was proposed in 2016.Zadeh, L. A. (2016). Stratification, target set reachability and incremental enlargement principle. Information Sciences, 354, 131-139.
|
|
21, 1975, pp. 89-96. and "Ajtai Fagin games" Miklos Ajtai and Ronald Fagin, "Reachability is harder for directed than for undirected finite graphs". Journal of Symbolic Logic 55, 1, March 1990, pp. 113-150. Preliminary version appeared in Proc.
|
|
The parallelism comes from: (1) the reachability queries can be parallelized more easily (e.g. by a BFS, and it can be fast if the diameter of the graph is small); and (2) the independence between the subtasks in the divide-and-conquer process. This algorithm performs well on real-world graphs, but does not have theoretical guarantee on the parallelism (consider if a graph has no edges, the algorithm requires O(n) levels of recursions). Blelloch et al.. in 2016 shows that if the reachability queries are applied in a random order, the cost bound of O(n log n) still holds.
|
|
Even C language macros can be used, if C header files are present. External declarations must be made available to the TNSDL translator. The TNSDL translator is a proprietary tool. A source code (reachability) analyser has also been developed specifically for TNSDL.
|
|
With these definitions, a topological ordering of the DAG is the same thing as a linear extension of this partial order. Conversely, any partial ordering on a finite set may be defined as the reachability relation in a DAG. One way of doing this is to define a DAG that has a vertex for every object in the partially ordered set, and an edge xy for every pair of objects for which x ≤ y. An alternative way of doing this is to use the transitive reduction of the partial ordering; in general, this produces DAGs with fewer edges, but the reachability relation in these DAGs is still the same partial order.
|
|
More abstractly, the reachability relation in a DAG forms a partial order, and any finite partial order may be represented by a DAG using reachability. Important polynomial time computational problems on DAGs include topological sorting (computing a topological ordering), construction of the transitive closure and transitive reduction (the largest and smallest DAGs with the same reachability relation, respectively) of sets, and the closure problem, in which the goal is to find a minimum-weight subset of vertices with no edges connecting them to the rest of the graph. Transforming a directed graph with cycles into a DAG by deleting as few vertices or edges as possible (the feedback vertex set and feedback edge set problem, respectively) is an NP-hard problem, but any directed graph can be made into a DAG (its condensation) by contracting each strongly connected component into a single supervertex. The problems of finding shortest paths and longest paths can be solved on DAGs in linear time, in contrast to arbitrary graphs for which shortest path algorithms are slower and longest path problems are NP-hard.
|
|
In 2011, Tor2web, Tor Hidden Service proxy designed by Aaron Swartz and Virgil Griffith, became part of the GlobaLeaks project as a component intended for extending platforms reachability to traditional HTTPS connections. In 2012, the Hermes Center for Transparency and Digital Human Rights NGO was founded in Italy.
|
|
However, the drawback of the collapsed backbone is that if the box housing the backbone is down or there are reachability problem to the central location, the entire network will crash. These problems can be minimized by having redundant backbone boxes as well as having secondary/backup backbone locations.
|
|
Labels are distributed between LERs and LSRs using the Label Distribution Protocol (LDP). LSRs in an MPLS network regularly exchange label and reachability information with each other using standardized procedures in order to build a complete picture of the network so they can then use to forward packets.
|
|
Methods for checking both safety and liveness properties have been developed and intensively studied over the last 20 years. It has been shown that the state reachability problem for timed automata is decidable,Rajeev Alur , David L. Dill. 1994 A Theory of Timed Automata. In Theoretical Computer Science, vol.
|
|
SP-DEVS has been designed to support verification analysis of its networks by guaranteeing to obtain a finite-vertex reachability graph of the original networks, which had been an open problem of DEVS formalism for roughly 30 years. To get such a reachability graph of its networks, SP-DEVS has been imposed the three restrictions: # finiteness of event sets and state set, # the lifespan of a state can be scheduled by a rational number or infinity, and # preserving the internal schedule from any external events. Thus, SP-DEVS is a sub-class of both DEVS and FD-DEVS. These three restrictions lead that SP-DEVS class is closed under coupling even though the number of states are finite.
|
|
Standard Petri net properties like reachability, boundedness and liveness show a mixed picture. A paper Michael Köhler- Bußmeier: A Survey of Decidability Results for Elementary Object Systems: Fundamenta Informaticae, Vol. 130, No 1, pp. 99-123, 2014 of Köhler-Bußmeier gives a survey on decidability results for elementary object systems.
|
|
A transitive tournament on 8 vertices. A tournament in which ((a \rightarrow b) and (b \rightarrow c)) \Rightarrow (a \rightarrow c) is called transitive. In other words, in a transitive tournament, the vertices may be (strictly) totally ordered by the edge relation, and the edge relation is the same as reachability.
|
|
A directed acyclic graph (regardless of planarity) has a dominance drawing if and only if the partially ordered set of its vertices, ordered by reachability, has order dimension two. The (rotated) dominance drawing of a transitively reduced directed acyclic graph may be used as a Hasse diagram of the corresponding partial order.
|
|
The comparator circuit evaluation problem can be solved in polynomial time, and so CC is contained in P ("circuit universality"). On the other hand, comparator circuits can solve directed reachability, and so CC contains NL. There is a relativized world in which CC and NC are incomparable, and so both containments are strict.
|
|
The link-state message giving information about the neighbors is recomputed, and then flooded throughout the network, whenever there is a change in the connectivity between the node and its neighbors; e.g., when a link fails. Any such change will be detected by the reachability protocol which each node runs with its neighbors.
|
|
Simulation-aided reachability and local gain analysis for nonlinear dynamical systems. In: Proc. of the IEEE Conference on Decision and Control. pp. 4097–4102.A. Chakraborty, P. Seiler, and G. Balas, “Susceptibility of F/A-18 Flight Controllers to the Falling-Leaf Mode: Nonlinear Analysis,” AIAA Journal of Guidance, Control, and Dynamics, Vol.
|
|
The Complexity Profile Graph"Visualization and Measurement of Source Code" (CPG) is a statement-level complexity diagram. Its purpose is to aid in identifying overly complex areas of source code. jGRASP generates CPGs for both Java and Ada. The metric includes common measures, such as reachability and content complexity, which can be displayed individually.
|
|
Alternative analysis tools include: AVISPA (for reachability and correspondence assertions), KISS (for static equivalence), YAPA (for static equivalence). CryptoVerif for verification of security against polynomial time adversaries in the computational model. The Tamarin Prover is a modern alternative to ProVerif, with excellent support for Diffie- Hellman equational reasoning, and verification of observational equivalence properties.
|
|
Construction of a trivially perfect graph from nested intervals and from the reachability relationship in a tree In graph theory, a trivially perfect graph is a graph with the property that in each of its induced subgraphs the size of the maximum independent set equals the number of maximal cliques., definition 2.6.2, p.34; .
|
|
The reachability problem consists in deciding, given a channel system S and two initial configurations \gamma and \gamma' whether there is a run of S from \gamma to \gamma'. This problem is undecidable over perfect channel systems and decidable but nonprimitive recursive over lossy channel system. This problem is decidable over machine capable of insertion of errors .
|
|
Providing a sequence of recommendations becomes increasingly complex, and must take into account each location, the time, weather, reachability, etc., before providing any suggestion. These are generally known as context-aware recommendations, and tend to provide places that other people (possibly the user's friends) visited following an initial visit to the location of the user's first recommendation.
|
|
Let be the distance of the object A to the k-th nearest neighbor. Note that the set of the k nearest neighbors includes all objects at this distance, which can in the case of a "tie" be more than k objects. We denote the set of k nearest neighbors as . Illustration of the reachability distance.
|
|
ProVerif is a software tool for automated reasoning about the security properties found in cryptographic protocols. The tool has been developed by Bruno Blanchet. Support is provided for cryptographic primitives including: symmetric & asymmetric cryptography; digital signatures; hash functions; bit- commitment; and signature proofs of knowledge. The tool is capable of evaluating reachability properties, correspondence assertions and observational equivalence.
|
|
Mirsky's theorem can be restated in terms of directed acyclic graphs (representing a partially ordered set by reachability of their vertices), as the statement that there exists a graph homomorphism from a given directed acyclic graph G to a k-vertex transitive tournament if and only if there does not exist a homomorphism from a (k + 1)-vertex path graph to G. For, the largest path graph that has a homomorphism to G gives the longest chain in the reachability ordering, and the sets of vertices with the same image in a homomorphism to a transitive tournament form a partition into antichains. This statement generalizes to the case that G is not acyclic, and is a form of the Gallai–Hasse–Roy–Vitaver theorem on graph colorings and orientations .
|
|
The transitive closure of a given DAG, with vertices and edges, may be constructed in time by using either breadth-first search or depth-first search to test reachability from each vertex., p. 495. Alternatively, it can be solved in time where is the exponent for fast matrix multiplication algorithms; this is a theoretical improvement over the bound for dense graphs., p. 496.
|
|
USTCON is a special case of STCON (directed reachability), the problem of determining whether a directed path between two vertices in a directed graph exists, which is complete for NL. Because USTCON is SL-complete, most advances that impact USTCON have also impacted SL. Thus they are connected, and discussed together. In October 2004 Omer Reingold showed that SL = L.
|
|
Optimal Choice: Computation in realizing Optimal Choice can be very simple or very complex. A simple rule in Optimal Choice is to accept whatever is reached, Reward As You Go (RAYG). A Reachable Optimality computation reduces into optimizing reachability when RAYG is adopted. The Optimal Choice computation can be more complex when multiple NE strategies present in a reached game. 2\.
|
|
EGP was developed by Bolt, Beranek and Newman in the early 1980s. It was first described in RFC 827 and formally specified in RFC 904. EGP is a simple reachability protocol, and, unlike modern distance-vector and path-vector protocols, it is limited to tree-like topologies. During the early days of the Internet, EGP version 3 (EGP3) was used to interconnect autonomous systems.
|
|
Prior C++ standards provided for programmer-driven garbage collection via `set_new_handler`, but gave no definition of object reachability for the purpose of automatic garbage collection. C++11 defines conditions under which pointer values are "safely derived" from other values. An implementation may specify that it operates under strict pointer safety, in which case pointers that are not derived according to these rules can become invalid.
|
|
The protocol is defined by the behavior of the two entities, which is given in the second diagram in the form of two state machines. Here the symbol "!" means sending a message, and "?" means consuming a received message. The initial states are the states "1". The third diagram shows the result of the reachability analysis for this protocol in the form of a global state machine.
|
|
Each entry in the routing table contains the destination network, the next router and the path to reach the destination. Border Gateway Protocol (BGP) is an example of a path vector protocol. In BGP, the autonomous system boundary routers (ASBR) send path- vector messages to advertise the reachability of networks. Each router that receives a path vector message must verify the advertised path according to its policy.
|
|
Due to this relaxation there is no longer OPNA problem, but there is also one limitation that a time-line abstraction which can be used for abstracting elapsed times of SP-DEVS networks is no longer useful for FD- DEVS network [Hwang05]. But another time abstraction method [Dill89] which was invented by Prof. D. Dill can be applicable to obtain a finite-vertex reachability graph for FD-DEVS networks.
|
|
Most of the work on protocol modeling use finite-state machines (FSM) to model the behavior of the distributed entities (see also Communicating finite-state machines). However, this model is not powerful enough to model message parameters and local variables. Therefore often so-called extended FSM models are used, such as supported by languages like SDL or UML state machines. Unfortunately, reachability analysis becomes much more complex for such models.
|
|
The shopping center enlargement plans are supported by Helsinki City Planning Department's proposals to improve the reachability of Munkkivuori by public transportation. These proposals go by the name "Ratikka 2015" ("Tram 2015") study and include expanding the tram network to cover Munkkivuori. A new tram line number 5 from Kalasatama to Munkkivuori via Kruununhaka is brought up in the study. Alternatively the existing tram line number 4T could be rerouted to Munkkivuori.
|
|
AEP (AppleTalk Echo Protocol) is a transport layer protocol designed to test the reachability of network nodes. AEP generates packets to be sent to the network node and is identified in the Type field of a packet as an AEP packet. The packet is first passed to the source DDP. After it is identified as an AEP packet, it is forwarded to the node where the packet is examined by the DDP at the destination.
|
|
SCTP provides redundant paths to increase reliability. SCTP Multihoming Each SCTP end point needs to check reachability of the primary and redundant addresses of the remote end point using a heartbeat. Each SCTP end point needs to acknowledge the heartbeats it receives from the remote end point. When SCTP sends a message to a remote address, the source interface will only be decided by the routing table of the host (and not by SCTP).
|
|
In anomaly detection, the local outlier factor (LOF) is an algorithm proposed by Markus M. Breunig, Hans-Peter Kriegel, Raymond T. Ng and Jörg Sander in 2000 for finding anomalous data points by measuring the local deviation of a given data point with respect to its neighbours. LOF shares some concepts with DBSCAN and OPTICS such as the concepts of "core distance" and "reachability distance", which are used for local density estimation.
|
|
The fastest method is DBSCAN, which uses a defined distance to differentiate between dense groups of information and sparser noise. Moreover, HDBSCAN can self-adjust by using a range of distances instead of a specified one. Lastly, the method OPTICS creates a reachability plot based on the distance from neighboring features to separate noise from clusters of varying density. These methods still require the user to provide the cluster center and cannot be considered automatic.
|
|
PAT (Process Analysis Toolkit) is a self-contained framework for composing, simulating and reasoning of concurrent, real-time systems and other possible domains. It comes with user friendly interfaces, featured model editor and animated simulator. Most importantly, PAT implements various model checking techniques catering for different properties such as deadlock-freeness, divergence-freeness, reachability, LTL properties with fairness assumptions, refinement checking and probabilistic model checking. To achieve good performance, advanced optimization techniques are implemented in PAT, e.g.
|
|
This influx in reachability has also made it easier to commit unlawful actions within an auction. In 2002, online auctions were projected to account for 30% of all online e-commerce due to the rapid expansion of the popularity of the form of electronic commerce. Online auctions include business to business (B2B), business to consumer (B2C), and consumer to consumer (C2C) auctions. The largest online auction site is eBay, which was the first to support person-to- person transactions.
|
|
Coverability can be decided for any well- structured system, and so can reachability of a given control state, by the backward algorithm of Abdulla et al. or for specific subclasses of well- structured systems (subject to strict monotonicity,Alain Finkel and Philippe Schnoebelen, Well-Structured Transition Systems Everywhere!, Theoretical Computer Science 256(1–2), pages 63–92, 2001. e.g. in the case of unbounded Petri nets) by a forward analysis based on a Karp-Miller coverability graph.
|
|
If there are several iBGP routes from the neighbor, the one with the highest LOCAL_PREFERENCE is selected unless there are several routes with the same LOCAL_PREFERENCE. In the latter case the route selection process moves to the next tie breaker. While LOCAL_PREFERENCE is the first rule in the standard, once reachability of the NEXT_HOP is verified, Cisco and several other vendors first consider a decision factor called WEIGHT which is local to the router (i.e. not transmitted by BGP).
|
|
The concept of trash culture should not be confused or merged with the concept of "kitsch", even if the two are correlated. Kitsch is linked to art in a permanent way, but it is also a social phenomenon which establishes itself as a way of being: in Western society it is characterized by the limitation of the artist's space of creation. Kitsch is essentially multiplication and reachability. It is based on the consumeristic civilization which creates to produce, and produces to consume.
|
|
For reachability analysis, the local entities are modeled by their states and transitions. An entity changes state when it sends a message, consumes a received message, or performs an interaction at its local service interface. The global state s = (s_1, s_2, ..., s_n, medium) of a system with n entities Note: In the case of protocol analysis, there are normally only two entities. is determined by the states s_i (i=1, ... n) of the entities and the state of the communication medium.
|
|
Tools for the activities of protocol verification, entity implementation and test suite development can be developed when the protocol specification is written in a formalized language which can be understood by the tool. As mentioned, formal specification languages have been proposed for protocol specification, and the first methods and tools where based on finite-state machine models. Reachability analysis was proposed to understand all possible behaviors of a distributed system, which is essential for protocol verification. This was later complemented with model checking.
|
|
This is one of the few places in Kerala where the nature is not largely affected by human invasion, thanks to the limited reachability. But the future does not look promising because of the increasing tendency of visitors to make it as a drinking spot. The observatory tower is in a poor condition as the walls and barricades are broken or destroyed. The surroundings of the tower are littered with beer bottles and like any other tourist spots, plastic is the major threat here too.
|
|
A dominance drawing Dominance drawing is a style of graph drawing of directed acyclic graphs that makes the reachability relations between vertices visually apparent. In dominance drawing, vertices are placed at distinct points of the Euclidean plane and a vertex v is reachable from another vertex u if and only if both Cartesian coordinates of v are greater than or equal to the coordinates of u. The edges of a dominance drawing may be drawn either as straight line segments, or, in some cases, as polygonal chains.
|
|
Those are in fact commonly used to performance tune on a use case basis. For example, if you are going to iterate over a collection of 1000 objects, you don’t want to do 1000 RPC’s. Giving the collection of references to a call to groupRead will use a single RPC and load all objects. Similarly, you can make a call to getClosure which will use groupRead behavior to load all referenced objects in a graph from the starting point, down to your specified level of reachability.
|
|
Ping is a computer network administration software utility used to test the reachability of a host on an Internet Protocol (IP) network. It is available for virtually all operating systems that have networking capability, including most embedded network administration software. Ping measures the round-trip time for messages sent from the originating host to a destination computer that are echoed back to the source. The name comes from active sonar terminology that sends a pulse of sound and listens for the echo to detect objects under water.
|
|
Paping (pronounced pah ping) is a computer network administration utility used to test the reachability of a host on an Internet Protocol (TCP/IP) network and to measure the time it takes to connect to a specified port. The name is a play on the word ping, another computer network administration utility. Because ICMP can be used to identify the operating system of a remote machine, it is sometimes blocked. If ICMP is blocked, ping cannot be used to identify if the service is responding.
|
|
P is known to contain many natural problems, including the decision versions of linear programming, calculating the greatest common divisor, and finding a maximum matching. In 2002, it was shown that the problem of determining if a number is prime is in P.Manindra Agrawal, Neeraj Kayal, Nitin Saxena, "PRIMES is in P", Annals of Mathematics 160 (2004), no. 2, pp. 781–793. The related class of function problems is FP. Several natural problems are complete for P, including st-connectivity (or reachability) on alternating graphs.
|
|
Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems (AS) on the Internet. BGP is classified as a path-vector routing protocol, and it makes routing decisions based on paths, network policies, or rule-sets configured by a network administrator. BGP used for routing within an autonomous system is called Interior Border Gateway Protocol, Internal BGP (iBGP). In contrast, the Internet application of the protocol is called Exterior Border Gateway Protocol, External BGP (eBGP).
|
|
"Conservative" garbage collection capabilities can be added to any programming language that lacks it as a built-in feature, and libraries for doing this are available for C and C++ programs. A conservative collector finds and reclaims most, but not all, unreachable memory. Although the memory manager can recover unreachable memory, it cannot free memory that is still reachable and therefore potentially still useful. Modern memory managers therefore provide techniques for programmers to semantically mark memory with varying levels of usefulness, which correspond to varying levels of reachability.
|
|
Reif et al. prove that if the n-body reachability problem is defined as follows – given n bodies satisfying a fixed electrostatic potential law, determining if a body reaches a destination ball in a given time bound where we require a poly(n) bits of accuracy and the target time is poly(n) is in PSPACE. On the other hand, if the question is whether the body eventually reaches the destination ball, the problem is PSPACE-hard. These bounds are based on similar complexity bounds obtained for ray tracing.
|
|
Egonetwork analysis focuses on network characteristics such as size, relationship strength, density, centrality, prestige and roles such as isolates, liaisons, and bridges. Such analyses, are most commonly used in the fields of psychology or social psychology, ethnographic kinship analysis or other genealogical studies of relationships between individuals. Subset level: Subset levels of network research problems begin at the micro-level, but may cross over into the meso-level of analysis. Subset level research may focus on distance and reachability, cliques, cohesive subgroups, or other group actions or behavior.
|
|
For Internet access, Mobile IPv6 is a widely accepted solution to provide session continuity and reachability to the Internet for mobile nodes. While integrated solutions for usage of Mobile IPv6 in (non-vehicular) mobile ad hoc networks exist, a solution has been proposed that, built upon a Mobile IPv6 proxy-based architecture, selects the optimal communication mode (direct in-vehicle, vehicle–vehicle, and vehicle–roadside communication) and provides dynamic switching between vehicle–vehicle and vehicle–roadside communication mode during a communication session in case that more than one communication mode is simultaneously available.
|
|
His first research topic in computer science was related to neural networks. But soon he moved to the field of compiler construction, and wrote a paper on the description of the semantics of programming languages which was much cited. But in 1975 he moved to the very new field of computer networks and concentrated his efforts on the description, verification and implementation of communication protocols. He wrote a seminal paper on finite state description of protocols and proposed the approach of reachability analysis for the verification of the behavior of distributed systems.
|
|
A central focus of database theory is on understanding the complexity and power of query languages and their connection to logic. Starting from relational algebra and first-order logic (which are equivalent by Codd's theorem) and the insight that important queries such as graph reachability are not expressible in this language, more powerful language based on logic programming and fixpoint logic such as datalog were studied. Another focus was on the foundations of query optimization and data integration. Here most work studied conjunctive queries, which admit query optimization even under constraints using the chase algorithm.
|
|
The Secure Neighbor Discovery (SEND) protocol is a security extension of the Neighbor Discovery Protocol (NDP) in IPv6 defined in RFC 3971 and updated by RFC 6494. The Neighbor Discovery Protocol (NDP) is responsible in IPv6 for discovery of other network nodes on the local link, to determine the link layer addresses of other nodes, and to find available routers, and maintain reachability information about the paths to other active neighbor nodes (RFC 4861). NDP is insecure Holding IPv6 Neighbor Discovery to a Higher Standard of Security, community.infoblox.com, 2.10.
|
|
Robot movements, reachability analysis, collision and near-miss detection and cycle time reporting can be included when simulating the robot program. OLP does not interfere with production as the program for the robot is created outside the production process on an external computer. This method contradicts to the traditional on-line programming of industrial robots where the robot teach pendant is used for programming the robot manually. The time for the adoption of new programs can be cut from weeks to a single day, enabling the robotization of short-run production.
|
|
Well-formed Petri nets are a Petri net class jointly elaborated between the University of Paris 6 (Université P. & M. Curie) and the University of Torino in the early 1990s. It is a restriction of the high-level nets (or colored Nets) introduced by K. Jensen. The main advantage of Well Formed Nets is the notion of symbolic reachability graph that is composed of symbolic states. A symbolic state is a state representing several concrete states in the state space of the system described by the Petri net.
|
|
Thus, HSLS may fail in some circumstances requiring high assurance. While the papers describing HSLS do not focus on security, techniques such as digital signatures on routing updates can be used with HSLS (similar to OSPF with Digital Signatures), and BBN has implemented HSLS with digital signatures on neighbor discovery messages and link state updates. Such schemes are challenging in practice because in the ad hoc environment reachability of public key infrastructure servers cannot be assured. Like almost all routing protocols, HSLS does not include mechanisms to protect data traffic.
|
|
Conditionality: Realizable tradeoff between reachability and optimality depends primarily upon the initial bet capacity and how the bet capacity evolves along with the payoff table update path triggered by bet behavior and empowered by the underlying law of reward and punishment. Precisely, it is a sequence of conditional events where the next event happens upon reached status quo from experience path. 4\. Robustness: The more challenge a reachable optimality can accommodate, the more robust it is in terms of path integrity. There are also four computation features in the law of reachable optimality. 1\.
|
|
If a DAG has a reachability relation described by the partial order , then the transitive reduction of is a subgraph of that has an edge for every pair in the covering relation of . Transitive reductions are useful in visualizing the partial orders they represent, because they have fewer edges than other graphs representing the same orders and therefore lead to simpler graph drawings. A Hasse diagram of a partial order is a drawing of the transitive reduction in which the orientation of each edge is shown by placing the starting vertex of the edge in a lower position than its ending vertex..
|
|
However, uniqueness fails for graphs with (directed) cycles, and for infinite graphs not even existence is guaranteed. The closely related concept of a minimum equivalent graph is a subgraph of D that has the same reachability relation and as few edges as possible. The difference is that a transitive reduction does not have to be a subgraph of D. For finite directed acyclic graphs, the minimum equivalent graph is the same as the transitive reduction. However, for graphs that may contain cycles, minimum equivalent graphs are NP-hard to construct, while transitive reductions can be constructed in polynomial time.
|
|
The Internet utilizes copper communications and the optical networking backbone to enable the World Wide Web (WWW), the Internet of Things, video transfer and a broad range of information services. Participants in the Internet use a diverse array of methods of several hundred documented, and often standardized, protocols compatible with the Internet Protocol Suite and an addressing system (IP addresses) administered by the Internet Assigned Numbers Authority and address registries. Service providers and large enterprises exchange information about the reachability of their address spaces through the Border Gateway Protocol (BGP), forming a redundant worldwide mesh of transmission paths.
|
|
Some simulations also analyze physiological measures including metabolism, energy expenditure, and fatigue limits Cycle time studies, design and process validation, user comfort, reachability, and line of sight are other human-factors that may be examined in ergonomic simulation packages. Modeling and simulation of a task can be performed by manually manipulating the virtual human in the simulated environment. Some ergonomics simulation software permits interactive, real- time simulation and evaluation through actual human input via motion capture technologies. However, motion capture for ergonomics requires expensive equipment and the creation of props to represent the environment or product.
|
|
Given a dominance drawing of a directed acyclic graph D1 = (V, E1), inverting the interpretation of one axis results in a new relation one could call coreachability. Thus a point (xa, ya) could be considered coreachable from a point (xb, yb) whenever xa ≥ xb but ya ≤ yb. In this way, the dominance drawing may be seen to induce a second directed acyclic graph D2 = (V, E2) on the same vertex set. The pairs {≤1, ≤2} of partial orders on a shared ground set that permit such simultaneous representation by a single drawing—interpreted in terms of reachability and coreachability—are called codominant.
|
|
A series-parallel partial order, shown as a Hasse diagram. In order-theoretic mathematics, a series-parallel partial order is a partially ordered set built up from smaller series-parallel partial orders by two simple composition operations... The series-parallel partial orders may be characterized as the N-free finite partial orders; they have order dimension at most two.. They include weak orders and the reachability relationship in directed trees and directed series-parallel graphs. The comparability graphs of series-parallel partial orders are cographs. Series-parallel partial orders have been applied in job shop scheduling,.
|
|
The BGP method of PE auto-discovery is based on that used by Layer-3 MPLS VPNs to distribute VPN routes among PEs participating in a VPN. The BGP4 Multi-Protocol (BGP-MP) extensions are used to distribute VPN IDs and VPN-specific reachability information. Since IBGP requires either a full mesh of BGP sessions or the use of a route reflector, enabling the VPN ID in a participating PEs existing BGP configuration provides it with a list of all PEs in that VPN. Note that this method is for auto-discovery alone; LDP is still used for signaling.
|
|
Infer performs checks for null pointer exceptions, resource leaks, annotation reachability, missing lock guards, and concurrency race conditions in Android and Java code. It checks for null pointer problems, memory leaks, coding conventions and unavailable API’s in C, C++ and Objective C. Infer uses a technique called bi- abduction Separation logic and bi-abduction, page, Infer project site. to perform a compositional program analysis that interprets program procedures independently of their callers. It is claimed that this enables Infer to scale to large codebases and to run quickly on code-changes in an incremental fashion, while still performing an inter-procedural analysis that reasons across procedure boundaries.
|
|
IPv6-to-IPv6 Network Prefix Translation (NPTv6) is an experimental specification for IPv6 to achieve the address-independence at the network edge, given by network address translation (NAT) in Internet Protocol version 4. It has fewer architectural problems than traditional IPv4 NAT; it is for example stateless and preserves the reachability attributed to the end-to-end principle. However, the method still lacks solutions to translate embedding IPv6 addresses, for example in IPsec, and requires a more complex DNS setup (split-horizon DNS). One use case for IPv6-IPv6 Network Prefix Translation is multihoming for small networks; this may also be implemented with DHCPv6.
|
|
In computational complexity theory, SL (Symmetric Logspace or Sym-L) is the complexity class of problems log-space reducible to USTCON (undirected s-t connectivity), which is the problem of determining whether there exists a path between two vertices in an undirected graph, otherwise described as the problem of determining whether two vertices are in the same connected component. This problem is also called the undirected reachability problem. It does not matter whether many-one reducibility or Turing reducibility is used. Although originally described in terms of symmetric Turing machines, that equivalent formulation is very complex, and the reducibility definition is what is used in practice.
|
|
For directed acyclic graphs whose reachability order has higher dimension, a weak dominance drawing is a drawing in which every edge is oriented upwards, rightwards, or both, but in which there exist pairs of vertices (u, v) for which u dominates v coordinatewise but v is not reachable from u in the graph. We said that a vertex u dominates another vertex v if the coordinates (u_x, u_y) of u are less or equal the coordinates (v_x, v_y) of v, i.e., u_x <= v_x and u_y <= v_y considering a XY-plane. The goal in this style of drawing is to minimize the number of such falsely implied paths.
|
|
Upward planar drawings are particularly important for Hasse diagrams of partially ordered sets, as these diagrams are typically required to be drawn upwardly. In graph-theoretic terms, these correspond to the transitively reduced directed acyclic graphs; such a graph can be formed from the covering relation of a partial order, and the partial order itself forms the reachability relation in the graph. If a partially ordered set has one minimal element, has one maximal element, and has an upward planar drawing, then it must necessarily form a lattice, a set in which every pair of elements has a unique greatest lower bound and a unique least upper bound., 6.7.
|
|
One important NL-complete problem is ST-connectivity (or "Reachability") (Papadimitriou 1994 Thrm. 16.2), the problem of determining whether, given a directed graph G and two nodes s and t on that graph, there is a path from s to t. ST-connectivity can be seen to be in NL, because we start at the node s and nondeterministically walk to every other reachable node. ST-connectivity can be seen to be NL-hard by considering the computation state graph of any other NL algorithm, and considering that the other algorithm will accept if and only if there is a (nondetermistic) path from the starting state to an accepting state.
|
|
Early accordions sounded four pitches for the seventh and diminished chords. Modern Stradella systems omit the 5th from these two chords, allowing for more versatility. For example, an augmented seventh chord can be created by using the dominant seventh chord button and adding an augmented 5th from the right- hand manual or from one of the bass or counterbass buttons. In most Russian layouts the diminished seventh chord row is moved by one button, so that the C diminished seventh chord is where the F diminished seventh chord would be in a standard Stradella layout; this is done in order to achieve a better reachability with the forefinger.
|
|
Reachability analysis was introduced in a paper of 1978 for the analysis and verification of communication protocols.. This paper was inspired by a paper by Bartlett et al. of 1968 K.A. Bartlett, R.A. Scantlebury and P.T. Wilkinson, A note on reliable full-duplex transmission over half- duplex links, C.ACM 12, 260 (1969). which presented the alternating bit protocol using finite-state modeling of the protocol entities, and also pointed out that a similar protocol described earlier had a design flaw. This protocol belongs to the Link layer and, under certain assumptions, provides as service the correct data delivery without loss nor duplication, despite the occasional presence of message corruption or loss.
|
|
More modern garbage collection schemes are often based on a notion of reachability – if you don't have a usable reference to the memory in question, it can be collected. Other garbage collection schemes can be based on reference counting, where an object is responsible for keeping track of how many references are pointing to it. If the number goes down to zero, the object is expected to release itself and allow its memory to be reclaimed. The flaw with this model is that it doesn't cope with cyclic references, and this is why nowadays most programmers are prepared to accept the burden of the more costly mark and sweep type of systems.
|
|
In computer networking and telecommunications, route flapping occurs when a router alternately advertises a destination network via one route then another (or as unavailable, and then available again) in quick sequence. Route flapping is caused by pathological conditions (hardware errors, software errors, configuration errors, intermittent errors in communications links, unreliable connections, etc.) within the network which cause certain reachability information to be repeatedly advertised and withdrawn. For example, link flap occurs when an interface on a router has a hardware failure that will cause the router to announce it alternately as "up" and "down". In networks with link-state routing protocols, route flapping will force frequent recalculation of the topology by all participating routers.
|
|
DBSCAN can be seen as special (efficient) variant of spectral clustering: Connected components correspond to optimal spectral clusters (no edges cut – spectral clustering tries to partition the data with a minimum cut); DBSCAN finds connected components on the (asymmetric) reachability graph. However, spectral clustering can be computationally intensive (up to O(n^3) without approximation and further assumptions), and one has to choose the number of clusters k for both the number of eigenvectors to choose and the number of clusters to produce with k-means on the spectral embedding. Thus, for performance reasons, the original DBSCAN algorithm remains preferable to a spectral implementation, and this relationship is so far only of theoretical interest.
|
|
Consider now what happens if both the link from A to C and the link from B to C vanish at the same time (this can happen if node C has crashed). A believes that C is still reachable through B, and B believes that C is reachable through A. In a simple reachability protocol, such as EGP, the routing loop will persist forever. In a naive distance vector protocol, such as the routing information protocol, the loop will persist until the metrics for C reach infinity (the maximum number of routers that a packet can traverse in RIP is 15. The value 16 is considered infinity and the packet is discarded).
|
|
Tannenbaum has done research in numerous areas including robust control, computer vision, and biomedical imaging, having almost 500 publications. He pioneered the field of robust control with the solution of the gain margin and phase margin problems using techniques from Nevanlinna–Pick interpolation theory, which was the first H-infinity type control problem solved. Tannenbaum used techniques from elliptic curves to show that the reachability does not imply pole assignability for systems defined over polynomial rings in two or more variables over an arbitrary field. He pioneered the use of partial differential equations in computer vision and biomedical imaging co-inventing with Guillermo Sapiro an affine-invariant heat equation for image enhancement.
|
|
The speaker node advertises the path, not the metric, of the nodes in its autonomous system or other autonomous systems. The path-vector routing algorithm is similar to the distance vector algorithm in the sense that each border router advertises the destinations it can reach to its neighboring router. However, instead of advertising networks in terms of a destination and the distance to that destination, networks are advertised as destination addresses and path descriptions to reach those destinations. The path, expressed in terms of the domains (or confederations) traversed so far, is carried in a special path attribute that records the sequence of routing domains through which the reachability information has passed.
|
|
A given BGP router may accept Network Layer Reachability Information (NLRI) UPDATEs from multiple neighbors and advertise NLRI to the same, or a different set, of neighbors. Conceptually, BGP maintains its own "master" routing table, called the Local Routing Information Base (Loc-RIB), separate from the main routing table of the router. For each neighbor, the BGP process maintains a conceptual Adjacent Routing Information Base, Incoming (Adj-RIB-In) containing the NLRI received from the neighbor, and a conceptual Adj-RIB-Out (Outgoing) for NLRI to be sent to the neighbor. "Conceptual", in the preceding paragraph, means that the physical storage and structure of these various tables are decided by the implementer of the BGP code.
|
|
Pearl has commented on the surrealism of the world, as well as (paradoxically) its similarity to our own. He writes, “The Lady’s experience is described as ‘so strange an adventure,’ in ‘so strange a place, and amongst such wonderful kind of creatures,’ ‘none like any of our world’...It seems anything is possible here,” and that, “near as it is, the Blazing World boasts a multitude of otherworldly marvels," but also believes that "the interstitial passageway exists as a wrinkle in space, a connecting disconnection that permits the Blazing World’s narrow reachability and legitimises its radical differences.” By "interstitial passageway," Pearl is referring to the unseen, unexplained path the protagonist and her captors traverse in the beginning of the story to reach the Blazing World.
|
|
In mathematics, a transitive reduction of a directed graph D is another directed graph with the same vertices and as few edges as possible, such that if there is a (directed) path from vertex v to vertex w in D, then there is also such a path in the reduction. Transitive reductions were introduced by , who provided tight bounds on the computational complexity of constructing them. More technically, the reduction is a directed graph that has the same reachability relation as D. Equivalently, D and its transitive reduction should have the same transitive closure as each other, and its transitive reduction should have as few edges as possible among all graphs with this property. The transitive reduction of a finite directed acyclic graph (a directed graph without directed cycles) is unique and is a subgraph of the given graph.
|
|
As an alternative analysis method against the sampling-based simulation method, an exhaustive generating behavior approach, generally called verification has been applied for analysis of DEVS models. It is proven that infinite states of a given DEVS model (especially a coupled DEVS model ) can be abstracted by behaviorally isomorphic finite structure, called a reachability graph when the given DEVS model is a sub-class of DEVS such as Schedule-Preserving DEVS (SP-DEVS), Finite & Deterministic DEVS (FD- DEVS) [HZ09], and Finite & Real-time DEVS (FRT-DEVS) [Hwang12]. As a result, based on the rechability graph, (1) dead-lock and live-lock freeness as qualitative properties are decidable with SP-DEVS [Hwang05], FD-DEVS [HZ06], and FRT-DEVS [Hwang12]; and (2) min/max processing time bounds as a quantitative property are decidable with SP-DEVS so far by 2012.
|
|
Every directed acyclic graph has a topological ordering, an ordering of the vertices such that the starting endpoint of every edge occurs earlier in the ordering than the ending endpoint of the edge. The existence of such an ordering can be used to characterize DAGs: a directed graph is a DAG if and only if it has a topological ordering. In general, this ordering is not unique; a DAG has a unique topological ordering if and only if it has a directed path containing all the vertices, in which case the ordering is the same as the order in which the vertices appear in the path.. The family of topological orderings of a DAG is the same as the family of linear extensions of the reachability relation for the DAG,. so any two graphs representing the same partial order have the same set of topological orders.
|
|
Any partial order may be represented (usually in more than one way) by a directed acyclic graph in which there is a path from x to y whenever x and y are elements of the partial order with . The graphs that represent series-parallel partial orders in this way have been called vertex series parallel graphs, and their transitive reductions (the graphs of the covering relations of the partial order) are called minimal vertex series parallel graphs. Directed trees and (two- terminal) series parallel graphs are examples of minimal vertex series parallel graphs; therefore, series parallel partial orders may be used to represent reachability relations in directed trees and series parallel graphs. The comparability graph of a partial order is the undirected graph with a vertex for each element and an undirected edge for each pair of distinct elements x, y with either or .
|
|
These graphs are closely related to partially ordered sets and lattices. The Hasse diagram of a partially ordered set is a directed acyclic graph whose vertices are the set elements, with an edge from x to y for each pair x, y of elements for which x ≤ y in the partial order but for which there does not exist z with x ≤ y ≤ z. A partially ordered set forms a complete lattice if and only if every subset of elements has a unique greatest lower bound and a unique least upper bound, and the order dimension of a partially ordered set is the least number of total orders on the same set of elements whose intersection is the given partial order. If the vertices of an st-planar graph are partially ordered by reachability, then this ordering always forms a two-dimensional complete lattice, whose Hasse diagram is the transitive reduction of the given graph.
|
|
In this framework, the -coordinate assignment again involves grouping elements of a partially ordered set (the vertices of the graph, with the reachability ordering on the vertex set) into layers (sets of vertices with the same -coordinate), which is the problem solved by the Coffman–Graham algorithm.. Although there exist alternative approaches than the Coffman–Graham algorithm to the layering step, these alternatives in general are either not able to incorporate a bound on the maximum width of a level or rely on complex integer programming procedures.. More abstractly, both of these problems can be formalized as a problem in which the input consists of a partially ordered set and an integer . The desired output is an assignment of integer level numbers to the elements of the partially ordered set such that, if is an ordered pair of related elements of the partial order, the number assigned to is smaller than the number assigned to , such that at most elements are assigned the same number as each other, and minimizing the difference between the smallest and the largest assigned numbers.
|
|