Numbers expressible as a difference of two Pisot numbers

On Complex Pisot Numbers That Are Roots of Borwein Trinomials

“…A real algebraic integer α > 1 is called a Pisot number after [1,2], if all the algebraic conjugates of α over the field of rational numbers Q (other than α itself) are of absolute value < 1. Pisot numbers attract a lot of attention in the study of number expansions with algebraic number bases [3,4], substitution tilings [5][6][7], integer sequences with particular regard to linear recurrences [8][9][10], distributions of the fractional parts of the powers of real numbers [11,12] and many other areas [13,14].…”