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Hall's theorem revisited - MaRDI portal

Hall's theorem revisited (Q2723513)

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scientific article; zbMATH DE number 1614783
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Hall's theorem revisited
scientific article; zbMATH DE number 1614783

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    5 July 2001
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    matching
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    Hall's theorem
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    Hall's theorem revisited (English)
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    The author gives a short inductive proof of Hall's well-known theorem about matchings in bipartite graphs. Using a simple directed graph in his argument he estimates the number of ways to extend a given matching which is not maximum by one edge. Since this number is always positive provided Hall's well-known condition on the cardinality of the neighbourhoods is satisfied, Hall's theorem follows. Like in R. Rizzi's recent proof of König's theorem about matchings in bipartite graphs [J. Graph Theory 33, No.~3, 138-139 (2000)] the argument is short and elegant.
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