Plünnecke–Ruzsa inequality

In additive combinatorics, the Plünnecke–Ruzsa inequality is an inequality that bounds the size of various sumsets of a set B {\displaystyle B} , given that there is another set A {\displaystyle A} so that A + B {\displaystyle A+B} is not much larger than A {\displaystyle A} . A slightly weaker version of this inequality was originally proven and published by Helmut Plünnecke (1970).