Tetranomial Thue equations

Let F(x,y) be an irreducible binary form of degree n⩾6 with exactly four nonzero terms. Assuming certain conditions relating the coefficients and the degrees of the different terms are satisfied, we prove upper bounds on the number of equivalent pairs of nontrivial solutions of the Thue equation |F(x,y)|=1. Improved bounds are provided for a variety of cases, where more information about the form is known.