On some $q$-analog of an initial value problem with infinite order irregular singularity and Mahler transforms

Abstract

A family of $q$-difference-differential equations in two complex variables is studied, under the action of a so-called Mahler transform on time variable. The appearance of a leading formal $q$-difference operator of irregular type in the equation guarantees the existence of a formal solution to the main problem in time variable, which turns out to be obtained after a $q$-analog of Borel-Laplace procedure. Such formal solution to the main problem is $G_q$-summable along certain directions. The $G_q$-sums of such formal solutions do not in general satisfy the initial problem but rather turns out to be the analytic solutions to some related pseudo $q$-difference-differential equation.