Erdős–Szekeres theorem

The Erdős–Szekeres theorem is a significant result in combinatorial geometry and discrete mathematics. It addresses the problem of monotone subsequences in sequences of points in the plane. The theorem states that for any integer \( n \), any sequence of \( n^2 \) distinct points in the plane, no three of which are collinear, contains either: 1. An increasing subsequence of length \( n \), or 2. A decreasing subsequence of length \( n \).