Exemple de utilizare a Undirected graph în Engleză și traducerile lor în Română
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Undirected graphs.
Counting the number of Eulerian circuits on undirected graphs is much more difficult.
In the symmetric TSP, the distance between two cities is the same in each opposite direction,forming an undirected graph.
Covers of undirected graphs by convex sets.
The number of different Hamiltonian cycles in a complete undirected graph on n vertices is(n- 1)!
An undirected graph can be decomposed into edge-disjoint cycles if and only if all of its vertices have even degree.
Transitive tournaments play a role in Ramsey theory analogous to that of cliques in undirected graphs.
This implies, for example,that the number of triangles in an undirected graph G is exactly the trace of A3 divided by 6.
Undirected graphs often use the latter convention of counting loops twice, whereas directed graphs typically use the former convention.
In the maximum clique problem,the input is an undirected graph, and the output is a maximum clique in the graph. .
An undirected graph has an Eulerian cycle if and only if every vertex has even degree, and all of its vertices with nonzero degree belong to a single connected component.
An Eulerian trail,[3] orEuler walk in an undirected graph is a walk that uses each edge exactly once.
In every undirected graph, there is an equivalence relation on the vertices according to which two vertices are related to each other whenever there are two edge-disjoint paths connecting them.
In the mathematical field of graph theory,a complete graph is a simple undirected graph in which every pair of distinct vertices is connected by a unique edge.
An undirected graph has an Eulerian trail if and only if exactly zero or two vertices have odd degree, and all of its vertices with nonzero degree belong to a single connected component.
A 2004 result by Omer Reingold shows that USTCON,the problem of whether there exists a path between two vertices in a given undirected graph, is in L, showing that L= SL, since USTCON is SL-complete.[4].
The convention followed here(for undirected graphs) is that each edge adds 1 to the appropriate cell in the matrix, and each loop adds 2.
The maximum clique problem may be solved using as a subroutine an algorithm for the maximal clique listing problem, because the maximum clique must be included among all the maximal cliques.[18] In the k-clique problem,the input is an undirected graph and a number k.
It differs from an ordinary or undirected graph, in that the latter is defined in terms of unordered pairs of vertices, which are usually called edges, arcs, or lines.
If there are multiple maximum cliques, one of them may be chosen arbitrarily.[15] In the weighted maximum clique problem,the input is an undirected graph with weights on its vertices(or, less frequently, edges) and the output is a clique with maximum total weight.
In undirected graphs the set of edges of a cycle can be traversed by a walk in either of two directions, giving two possible directed cycles for every undirected cycle.
In the mathematical area of graph theory, a clique(/ˈkliːk/ or/ˈklɪk/)is a subset of vertices of an undirected graph such that its induced subgraph is complete; that is, every two distinct vertices in the clique are adjacent.
The maximum clique problem is the special case in which all weights are equal.[16] As well as the problem of optimizing the sum of weights, other more complicated bicriterion optimization problems have also been studied.[17] In the maximal clique listing problem,the input is an undirected graph, and the output is a list of all its maximal cliques.
A hypergraph is a combinatorial structure that, like an undirected graph, has vertices and edges, but in which the edges may be arbitrary sets of vertices rather than having to have exactly two endpoints.
Because each entry in the adjacency matrix requires only one bit, it can be represented in a very compact way, occupying only| V|2/8 bytes to represent a directed graph, or(by using a packed triangular format and only storing the lower triangular part of the matrix) approximately|V|2/16 bytes to represent an undirected graph.
Many of these generalized notions of cliques can also be found by constructing an undirected graph whose edges represent related pairs of actors from the social network, and then applying an algorithm for the clique problem to this graph.[2].
If a finite undirected graph has even degree at each of its vertices, regardless of whether it is connected, then it is possible to find a set of simple cycles that together cover each edge exactly once: this is Veblen's theorem.[8]When a connected graph does not meet the conditions of Euler's theorem, a closed walk of minimum length covering each edge at least once can nevertheless be found in polynomial time by solving the route inspection problem.
In some variations of this problem, the output should list all cliques of size k.[19] In the clique decision problem,the input is an undirected graph and a number k, and the output is a Boolean value: true if the graph contains a k-clique, and false otherwise.[20].
In this representation, the nodes of the singly linked list may be interpreted as edge objects; however,they do not store the full information about each edge(they only store one of the two endpoints of the edge) and in undirected graphs there will be two different linked list nodes for each edge(one within the lists for each of the two endpoints of the edge).
In his 1736 paper on the Seven Bridges of Königsberg, widely considered to be the birth of graph theory,Leonhard Euler proved that, for a finite undirected graph to have a closed walk that visits each edge exactly once, it is necessary and sufficient that it be connected except for isolated vertices(that is, all edges are contained in one component) and have even degree at each vertex.