Multiple solutions for a fractional double phase problem with <inline-formula><tex-math id="M1">$ p(t) $</tex-math></inline-formula>-Laplace operator

In this work, we investigate a double-phase problem involving Riemann-Liouville derivative and a $ p(t) $-Laplacian operator. More precisely, we will use a variational method with the critical theorem of Bonanno and Marano to prove the existence of at least three nontrivial solutions for such a problem. An illustrative example is presented at the end of this work to enhance the validity of our main results.