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    A new proof on the Ramsey number of matchings

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    For given simple graphs H1,H2,…,HcH_{1},H_{2},\ldots,H_{c}, the Ramsey number r(H1,H2,…,Hc)r(H_{1},H_{2},\ldots,H_{c}) is the smallest positive integer nn such that every edge-colored KnK_{n} with cc colors contains a subgraph isomorphic to HiH_{i} in color ii for some i∈{1,2,…,c}i\in\{1,2,\ldots,c\}. A critical graph of r(H1,H2,…,Hc)r(H_1,H_2,\ldots,H_c) is an edge-colored complete graph on r(H1,H2,…,Hc)βˆ’1r(H_1,H_2,\ldots,H_c)-1 vertices with cc colors which contains no subgraph isomorphic to HiH_{i} in color ii for any i∈{1,2,…,c}i\in \{1,2,\ldots,c\}. For n1β‰₯n2β‰₯…β‰₯ncβ‰₯1n_1\geq n_2\geq \ldots\geq n_c\geq 1, Cockayne and Lorimer (The Ramsey number for stripes, J. Austral. Math. Soc. 19 (1975) 252--256.) showed that r(n1K2,n2K2,…,ncK2)=n1+1+βˆ‘i=1c(niβˆ’1)r(n_{1}K_{2},n_{2}K_{2},\ldots,n_{c}K_{2})=n_{1}+1+ \sum\limits_{i=1}^c(n_{i}-1), in which niK2n_{i}K_{2} is a matching of size nin_{i}. In this paper, using Gallai-Edmonds Structure Theorem, we give a new proof on the value of r(n1K2,n2K2,…,ncK2)r(n_{1}K_{2},n_{2}K_{2},\ldots,n_{c}K_{2}) which also characterized all critical graphs
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