CZ-SK-MO 2005 Problem 6
Decide whether for every arrangement of the numbers in a sequence one can color these numbers with at most four different colors in such a way that the numbers of each color form a monotone subsequence.
Dataset text AI-MO AoPS. Quoted with source.
Solutions
No solution is on olymmath yet. Official and human solutions come first when they arrive. AI solutions come after them, with a label.
Similar problems
These problems have the most words in common with this statement.