Van der Waerden's theorem

Van der Waerden's theorem is a fundamental result in combinatorial mathematics, specifically in the area of Ramsey theory. The theorem states that for any positive integers \( r \) and \( k \), there exists a minimum integer \( N \) such that if the integers \( 1 \) to \( N \) are colored with \( r \) different colors, there will always be a monochromatic arithmetic progression of length \( k \).