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.

2013년 9월 25일 수요일

vector diagonal

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

2013년 9월 6일 금요일

Fault-free tiling


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.