Existence of a solution and a positive solution of a boundary value problem for a nonlinear fourth-order dynamic equation

In this paper, by using the Schauder fixed point theorem, we offer some existence criteria for a solution and a positive solution to the following fourth-order two-point boundary value problem on time scale TT: {u△△△△(t)−f(t,u(t),u△△(t))=0,t∈[a,ρ2(b)],u(a)=A,u(σ2(b))=B,u△△(a)=C, u△△(b)=D, where a,b∈Ta,b∈T and a