For given graphs G1,G2,...,Gk,k≥2, the multicolor Ramsey
number R(G1,G2,...,Gk) is the smallest integer n such that if
we arbitrarily color the edges of the complete graph of order n with k
colors, then it always contains a monochromatic copy of Gi colored with
i, for some 1≤i≤k. The bipartite Ramsey number $b(G_1, \cdots,
G_k)istheleastpositiveintegerbsuchthatanycoloringoftheedgesofK_{b,b}withkcolorswillresultinamonochromaticcopyofbipartiteG_iinthei−thcolor,forsomei,1 \le i \le k$.
There is very little known about R(G1,…,Gk) even for very
special graphs, there are a lot of open cases. In this paper, by using
bipartite Ramsey numbers we obtain the exact values of some multicolor Ramsey
numbers. We show that for sufficiently large n0 and three following cases:
- n1=2s, n2=2m and m−1<2s,
- n1=n2=2s,
- n1=2s+1, n2=2m and s<m−1<2s+1, we have
R(Cn0,Pn1,Pn2)=n0+⌊2n1⌋+⌊2n2⌋−2.
We prove that R(Pn,kK2,kK2)=n+2k−2 for large n. In addition, we
prove that for even k, R((k−1)K2,Pk,Pk)=3k−4. For s<m−1<2s+1
and t≥m+s−1, we obtain that R(tK2,P2s+1,P2m)=s+m+2t−2 where
Pk is a path on k vertices and tK2 is a matching of size t.
We also provide some new exact values or generalize known results for other
multicolor Ramsey numbers of paths, cycles, stripes and stars versus other
graphs.