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In mathematics, a graph product is a binary operation on graphs. Specifically, it is an operation that takes two graphs ''G''1 and ''G''2 and produces a graph ''H'' with the following properties: * The vertex set of ''H'' is the Cartesian product ''V''(''G''1) × ''V''(''G''2), where ''V''(''G''1) and ''V''(''G''2) are the vertex sets of ''G''1 and ''G''2, respectively. * Two vertices (''u''1, ''u''2) and (''v''1, ''v''2) of ''H'' are connected by an edge if and only if the vertices ''u''1, ''u''2, ''v''1, ''v''2 satisfy conditions of a certain type (see below). The following table shows the most common graph products, with ; denoting “is connected by an edge to”, and denoting non-connection. The operator symbols listed here are by no means standard, especially in older papers. \rightarrow J_ | |- | Tensor product (Categorical product) | and | | |- | Lexicographical product or | ''u''1 ∼ ''v''1 or ( ''u''1 = ''v''1 and ''u''2 ∼ ''v''2 ) | | |- | Strong product (Normal product, AND product) | ( ''u''1 = ''v''1 and ''u''2 ∼ ''v''2 ) or ( ''u''1 ∼ ''v''1 and ''u''2 = ''v''2 ) or ( ''u''1 ∼ ''v''1 and ''u''2 ∼ ''v''2 ) | | |- | Co-normal product (disjunctive product, OR product) | ''u''1 ∼ ''v''1 or ''u''2 ∼ ''v''2 | | |- | Modular product | or | | |- | Rooted product | see article | | |- | Kronecker product | see article | see article | see article |- | Zig-zag product | see article | see article | see article |- | Replacement product | | | |- | Homomorphic product | or | | |} In general, a graph product is determined by any condition for (''u''1, ''u''2) ∼ (''v''1, ''v''2) that can be expressed in terms of the statements ''u''1 ∼ ''v''1, ''u''2 ∼ ''v''2, ''u''1 = ''v''1, and ''u''2 = ''v''2. ==Mnemonic== Let be the complete graph on two vertices (i.e. a single edge). The product graphs , , and look exactly like the glyph representing the operator. For example, is a four cycle (a square) and is the complete graph on four vertices. The notation for lexicographic product serves as a reminder that this product is not commutative. 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「Graph product」の詳細全文を読む スポンサード リンク
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