Prove that there exists a four colored intersection in a four colored $100×100$ grid
141101
Russia (2000) contest:Prove the existence of a pair of rows and columns with intersections differently coloured
101493
Prove that one diagonal of a quadrilateral bisects the other
35864
Playing with numbers form $1$ to $n^2$ in an $n\times n$ grid
134652
Prove that the perpendicular bisectors of the sides of a triangle meet at a point
122151
Proof a $2^n$ by $2^n$ board can be filled using L shaped trominoes and 1 monomino
127185
How to test whether a set of four points can form a parallelogram
10724
Case of the 'mice problem' for $n=3$
97627
filling an occluded plane with the smallest number of rectangles
99606
Prove or disprove there exists a set of four numbers out of the $48$ positive integers of which product is a perfect square
120641
Intersection of three vector subspaces
57930
Chromatic polynomial properties
126583
Coloring points on an n-gon
127701
How many distinct ways are there to $2$-color the $8$ vertices of a cube?
19420
Find the set of largest contiguous rectangles to cover multiple areas
132996
Intersection of surface with parallel planes
59530
Efficiently finding the intersection of a variable number of sets of strings
78685
How to find all proper colorings (four coloring) of a graph with a brute force algorithm