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Informally, the reconstruction conjecture in graph theory says that graphs are determined uniquely by their subgraphs. It is due to Kelly〔Kelly, P. J., (A congruence theorem for trees ), ''Pacific J. Math.'' 7 (1957), 961–968.〕 and Ulam.〔Ulam, S. M., A collection of mathematical problems, Wiley, New York, 1960.〕 ==Formal statements== Given a graph , a vertex-deleted subgraph of is a subgraph formed by deleting exactly one vertex from . Clearly, it is an induced subgraph of . For a graph , the deck of G, denoted , is the multiset of all vertex-deleted subgraphs of . Each graph in is called a card. Two graphs that have the same deck are said to be hypomorphic. With these definitions, the conjecture can be stated as: * Reconstruction Conjecture: Any two hypomorphic graphs on at least three vertices are isomorphic. : (The requirement that the graphs have at least three vertices is necessary because both graphs on two vertices have the same decks.) Harary〔Harary, F., On the reconstruction of a graph from a collection of subgraphs. In ''Theory of Graphs and its Applications (Proc. Sympos. Smolenice, 1963)''. Publ. House Czechoslovak Acad. Sci., Prague, 1964, pp. 47–52.〕 suggested a stronger version of the conjecture: * Set Reconstruction Conjecture: Any two graphs on at least four vertices with the same sets of vertex-deleted subgraphs are isomorphic. Given a graph , an edge-deleted subgraph of is a subgraph formed by deleting exactly one edge from . For a graph , the edge-deck of G, denoted , is the multiset of all edge-deleted subgraphs of . Each graph in is called an edge-card. * Edge Reconstruction Conjecture: (Harary, 1964)〔 Any two graphs with at least four edges and having the same edge-decks are isomorphic. 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「reconstruction conjecture」の詳細全文を読む スポンサード リンク
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