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Maximal matching of a poset

asked 2020-09-04 06:55:52 -0500

daltop gravatar image

Hi,

I would like to know how to find a maximal matching (defined below) of a given finite poset.

 A matching  M in a poset X is a subset M of X x X such that:
   1) if (x, y) is in M, then x is an immediate predecessor of y (x<y and there is no element z such that x<z<y)
   2) each element x of X belongs to at most one element in M.

A matching of a poset is the same as a matching of its Hasse Diagram. I thought about using the matching() function for graphs, however, it seems that the Hasse diagram of a poset is a Digraph for Sage and so the matching function does not work.

By maximal matching I mean one with the maximal number of elements.

Any help would be appreciated.

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answered 2020-09-04 11:15:04 -0500

FrédéricC gravatar image

Maybe use the undirected Hasse diagram ?

sage: P=posets.PentagonPoset()                                                  
sage: G=P.hasse_diagram().to_undirected()                                       
sage: G.matching()                                                              
[(2, 3, None), (1, 4, None)]
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Asked: 2020-09-04 06:55:52 -0500

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Last updated: Sep 04