Convex bipartite graph: Difference between revisions

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cleanup, give more formal definition
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Let ''G'' = (''U'' ∪ ''V'', ''E'') be a bipartite graph, i.e, the vertex set is ''U'' ∪ ''V'' where ''U'' ∩ ''V'' = ∅.
Let ''N''<sub>''G''</sub>(''v'') denote the neighborhood of a vertex ''v''&nbsp;∈&nbsp;''V''.
The graph ''G'' is '''convex''' over ''U'' if and only if there exists a [[bijective]] mapping, ''f'':&nbsp;''U''&nbsp;→&nbsp;{&nbsp;1,&nbsp;2,&nbsp;...,&nbsp;|''U''|&nbsp;&minus;&nbsp;1,&nbsp;|''U|''}, such that for all ''v''&nbsp;∈&nbsp;''V'',
for any two vertices ''x'',''y''&nbsp;∈&nbsp;''N''<sub>''G''</sub>(''v'')&nbsp;⊆&nbsp;''U'' there does not exist a ''z''&nbsp;∉&nbsp;''N''<sub>''G''</sub>(''v'') such that ''f''(''x'')&nbsp;<&nbsp;''f''(''z'')&nbsp;<&nbsp;''f''(''y'').