经典Ramsey数R(4,20)、R(4,21)和R(4,22)的下界

Lower Bounds of Classical Ramsey Numbers R(4,20),R(4,21) and R(4,22)

本文构造了３个新的素数阶循环图，从而得到了３个Ｒａｍｓｅｙ数的下界：Ｒ（４，２０）≥２１２，Ｒ（４，２１）≥２４０，Ｒ（４，２２）≥２５８．

Three cyclic graphs of prime number are structured in this paper, which constitutes lower bounds of three Ramsey numbers: R(4,20)≥212,R(4,21)≥240,R(4,22)≥258.