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在这个例子，<math>H</math> 和 <math>G</math>是等价的， <math>H\equiv G</math>，而且两者的对偶图是强同构的：<math>H^*\cong G^*</math>

在这个例子，<math>H</math> 和 <math>G</math>是等价的， <math>H\equiv G</math>，而且两者的对偶图是强同构的：<math>H^*\cong G^*</math>

==Symmetric hypergraphs==

==对称超图 Symmetric hypergraphs==

The<math>r(H)</math> of a hypergraph <math>H</math> is the maximum cardinality of any of the edges in the hypergraph.  If all edges have the same cardinality ''k'', the hypergraph is said to be ''uniform'' or ''k-uniform'', or is called a ''k-hypergraph''.  A graph is just a 2-uniform hypergraph.

The<math>r(H)</math> of a hypergraph <math>H</math> is the maximum cardinality of any of the edges in the hypergraph.  If all edges have the same cardinality ''k'', the hypergraph is said to be ''uniform'' or ''k-uniform'', or is called a ''k-hypergraph''.  A graph is just a 2-uniform hypergraph.

由于超图的对偶性，边传递性的研究与顶点传递性的研究是相一致的。

由于超图的对偶性，边传递性的研究与顶点传递性的研究是相一致的。

==Transversals==

==横截面 Transversals==

A ''[[Transversal (combinatorics)|transversal]]'' (or "[[hitting set]]") of a hypergraph ''H'' = (''X'', ''E'') is a set <math>T\subseteq X</math> that has nonempty [[intersection (set theory)|intersection]] with every edge. A transversal ''T'' is called ''minimal'' if no proper subset of ''T'' is a transversal. The ''transversal hypergraph'' of ''H'' is the hypergraph (''X'', ''F'') whose edge set ''F'' consists of all minimal transversals of ''H''.

A ''[[Transversal (combinatorics)|transversal]]'' (or "[[hitting set]]") of a hypergraph ''H'' = (''X'', ''E'') is a set <math>T\subseteq X</math> that has nonempty [[intersection (set theory)|intersection]] with every edge. A transversal ''T'' is called ''minimal'' if no proper subset of ''T'' is a transversal. The ''transversal hypergraph'' of ''H'' is the hypergraph (''X'', ''F'') whose edge set ''F'' consists of all minimal transversals of ''H''.