 Cap set

A cap set is a subset $A\subseteq {\mathbb{F}}_3^n$ containing no three distinct points $x,y,z$ satisfying $x+y+z=0$. Equivalently, it contains no nonconstant three-term arithmetic progression.

A **Cap set** is a specific configuration in the context of combinatorial geometry and number theory, specifically concerning subsets of integers or points in higher-dimensional spaces. The concept is particularly related to the study of sets that avoid certain geometric configurations or progressions.