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A semicomplete digraph is a quasi-transitive digraph. There are extensions of quasi-transitive digraphs called k-quasi-transitive digraphs. [5] Oriented graphs are directed graphs having no opposite pairs of directed edges (i.e. at most one of (x, y) and (y, x) may be arrows of the graph).
In mathematics and computer science, graph theory is the study of graphs, which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of vertices (also called nodes or points) which are connected by edges (also called arcs, links or lines).
A signed digraph is a directed graph with signed arcs. Signed digraphs are far more complicated than signed graphs, because only the signs of directed cycles are significant. For instance, there are several definitions of balance, each of which is hard to characterize, in strong contrast with the situation for signed undirected graphs.
This is an accepted version of this page This is the latest accepted revision, reviewed on 11 February 2025. Long-term brain disorders causing impaired memory, thinking and behavior This article is about the cognitive disorder. For other uses, see Dementia (disambiguation). "Senile" and "Demented" redirect here. For other uses, see Senile (disambiguation) and Demented (disambiguation). Medical ...
Some 4% of U.S. adults aged 65 and older say they have been diagnosed with dementia, a rate that reached 13% for those at least 85-years old, according to a report of a national survey released on ...
A graph with three vertices and three edges. A graph (sometimes called an undirected graph to distinguish it from a directed graph, or a simple graph to distinguish it from a multigraph) [4] [5] is a pair G = (V, E), where V is a set whose elements are called vertices (singular: vertex), and E is a set of unordered pairs {,} of vertices, whose elements are called edges (sometimes links or lines).
In Welsh, the digraph ll fused for a time into a ligature.. A digraph (from Ancient Greek δίς (dís) 'double' and γράφω (gráphō) 'to write') or digram is a pair of characters used in the orthography of a language to write either a single phoneme (distinct sound), or a sequence of phonemes that does not correspond to the normal values of the two characters combined.
The reconstruction conjecture of Stanisław Ulam is one of the best-known open problems in graph theory.Using the terminology of Frank Harary [1] it can be stated as follows: If G and H are two graphs on at least three vertices and ƒ is a bijection from V(G) to V(H) such that G\{v} and H\{ƒ(v)} are isomorphic for all vertices v in V(G), then G and H are isomorphic.