On s-Bipartite Ramsey Numbers Stars, Matchings and Double Stars

Zhenming Bi1, James Halla2, Drake Olejniczak2, Ping Zhang2
1VOBA Solutions Boston, Massachusetts, USA
2Department of Mathematics Western Michigan University Kalamazoo, Michigan, USA

Abstract

For bipartite graphs \( F \) and \( H \) and a positive integer \( s \), the \( s \)-bipartite Ramsey number \( BR_s(F,H) \) of \( F \) and \( H \) is the smallest integer \( t \) with \( t \geq s \) such that every red-blue coloring of \( K_{s,t} \) results in a red \( F \) or a blue \( H \). We evaluate this number for all positive integers \( s \) when \( F \) and \( H \) are both stars, are both matchings, or one is a star and the other is a matching, as well as when \( F = H \) is an arbitrary double star.

Keywords: Ramsey number, bipartite Ramsey number, s-bipartite Ram- sey number, star, matching, double star.