翻訳と辞書 Words near each other ・ Reach Out Your Hand (And Touch Somebody) ・ Reach Records ・ Reach Sambath ・ Reach Skilled Volunteering ・ Reach stacker ・ Reach the Beach ・ Reach the Beach Relay ・ Reach the Rock ・ Reach the Sky ・ Reach the world ・ Reach To Teach Recruiting ・ Reach Up and Touch the Sky ・ Reach, Cambridgeshire ・ Reach-In ・ Reach-in oven ・ Reachability ・ Reachability problem ・ Reachback ・ Reached (novel) ・ Reacher Satellite Ground Terminal ・ Reachin' ・ Reachin' (A New Refutation of Time and Space) ・ Reachin' All Around ・ Reachin' Back ・ Reaching ・ Reaching (album) ・ Reaching (sculpture) ・ Reaching Across Illinois Library System ・ Reaching definition ・ Reaching Everyone By Exposing Lies Dictionary Lists mini英和辞書 mini和英辞書 Webster 1913 Latin-English FOLDOC Wikipedia English ウィキペディア

翻訳と辞書　辞書検索 [ 開発暫定版 ] スポンサード リンク Reachability ： ウィキペディア英語版 Reachability In graph theory, reachability refers to the ability to get from one vertex to another within a graph. We say that a vertex $s$ can reach a vertex $t$ (or that $t$ 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, it is sufficient to identify the connected components, as any pair of vertices in such a graph can reach each other if and only if they belong to the same connected component. The connected components of a graph can be identified in linear time. The remainder of this article focuses on reachability in a ''directed'' graph setting. == Definition == For a directed graph $G\; =\; (V,\; E)$, with vertex set $V$ and edge set $E$, the reachability relation of $G$ is the transitive closure of $E$, which is to say the set of all ordered pairs $(s,t)$ of vertices in $V$ for which there exists a sequence of vertices $v\_0\; =\; s,\; v\_1,\; v\_2,\; ...,\; v\_k\; =\; t$ such that the edge $(v\_,v\_i)$ is in $E$ for all $1\; \backslash leq\; i\; \backslash leq\; k$.〔.〕 If $G$ is acyclic, then its reachability relation is a partial order; any partial order may be defined in this way, for instance as the reachability relation of its transitive reduction.〔.〕 A noteworthy consequence of this is that since partial orders are anti-symmetric, if $s$ can reach $t$, then we know that $t$ ''cannot'' reach $s$. Intuitively, if we could travel from $s$ to $t$ and back to $s$, then $G$ would contain a cycle, contradicting that it is acyclic. If $G$ is directed but ''not'' acyclic (i.e. it contains at least one cycle), then its reachability relation will correspond to a preorder instead of a partial order. 〔.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Reachability」の詳細全文を読む スポンサード リンク 翻訳と辞書 : 翻訳のためのインターネットリソース Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.