Nice to meet you everyone.
I’m an engineer of Korea, working on image object recognition.
Any help (especially about my English translation) would be welcomed.
pilhoon-at-gmail-dot-com

2013년 9월 25일 수요일

vector diagonal

A cube has four diagonals. No two of them are perpendicular.

2013년 9월 6일 금요일

Fault-free tiling

Problem.

Answer.
http://www.umflint.edu/math/Field_Day/2005Problems/TeamEssayProblems2005.pdf
Ron Graham's Theorem.
It doesn't need to understand all theorems in that pdf. Just the last page(p.7) is enough to solve this problem.