We discuss, extend, improve and enrich results on simulation functions established by several authors. Furthermore, by using Lemma 2.1 of Radenovic et al. [Bull. Iran. Math. Soc., 2012, 38, 625],we get much shorter and nicer proofs than the corresponding ones in the existing literature.

We consider a parametric double phase problem with Robin boundary condition. We prove two existence theorems. In the first the reaction is [ ]-superlinear and the solutions produced are asymptotically big as [ ]. In the second the conditions on the reaction are essentially local at zero and the solutions produced are asymptotically small as [ ].

In 2012, Samet et al. introduced the notion ofα-ψ-contractive mapping and gave sufficient conditions for the existence of fixed points for this class of mappings. The purpose of our paper is to study the existence of fixed points for multivalued mappings, under anα-ψ-contractive condition of Ćirić type, in the setting of completeb-metric spaces. An application to integral equation is given.