On universal graphs without cliques or withour large bipartite graphs

Abstract

For every uncountable cardinal $\lambda$, suitable negations of the Generalized Continuum Hypothesis imply: - For all infinite $\alpha$ and $\beta$, there is no universal $K_{\alpha,\beta}$-free graphs in $\lambda$ - For all $\alpha\ge 3$, there is no universal $K_\alpha$-free graph in $\lambda$ The instance $K_{\omega,\omega_1}$ for $\lambda=\aleph_1$ was settled by Komjath and Pach from the principle $\diamondsuit(\omega_1)$.