Fredholmness property of \(M\)-elliptic pseudo-differential operator under change variable in its symbol (Q2251489)

In this paper the authors deal with a class of pseudo-differential operators on the \(n\)-dimensional torus, which are elliptic with respect to a certain weight. For this class they study their minimal and maximal extensions in the Lebesgue space \(L^p\). They prove that they are equal. Moreover, they give necessary and sufficient conditions for these operators to be Fredholm and prove that the Fredholm property is invariant under a change of variable.