A new existence theorem for right focal boundary value problems on a measure chain

In this paper we consider the following differential equation on a measure chain TuΔΔ(t)+f(u(σ(t)))=0,t∈[a,b]∩T, satisfying right focal boundary value conditions u(a)=0=uΔ(σ(b)). An existence result is obtained by using a fixed point theorem due to Krasnoselskii and Zabreiko. Our conditions imposed on f are very easy to verify and our result is even new for the special cases of differential equations and difference equations, as well as in the general time scale setting.