Sets of integers of the form A+2*A

Let A be a set of integers. The sumset A+A consists of all integers of the form a+a', where a and a' are in A. Let A+2*A denote the set of all integers of the form a+2a', where a and a' are in A. A general theorem of Nathanson, Orosz, O'Bryant, Ruzsa, and Silva implies that there exist finite sets A of integers such that card(A+A) > card(A+2*A). This talk will discuss issues related to these sets, including the computational problem of constructing explicit examples.

Kevin O'Bryant