**- Without Rahmat**

Today Rahmat left the dorm for helping his family till Wednesday. They are going to work in their garden, they have to manage their yield. I wish plague doesn't ruin their crops and have good crops.

Today was a bit boring because we had used to each other and Rahmat and I were good at making fun of Faraz :)

Faraz and I went out and eat ice cream again. Without Rahmat we can't play Rocket League and I have missed it so much.

**- Using Symmetry in Game Theory Problems**

I have encountered many game theory problems that needs to use Symmetry for solving them.

Today I stuck on one of them : 120E. Put Knight

Problem says that 2 players A and B are playing on a chessboard with size n*n. They take turns to put a Knight on board such that no two Knight threat each other. The player who can't move loses.

Solution : At first glance it seems so hard problem but actually it is so easy if you know how to use symmetry rules!

If n was odd : A can put first knight at center of the board and after that if B can find any place to put his knight then A also has a place to put his next knight , exactly in symmetric place of the B's knight respect to the center that certainly is empty ( also new 2 pieces can't threat each other ), so A is the winner !

If n was even : Divide the board to 2 same parts vertically. Every place that A puts his knight , B can put his knight at exact same row but in symmetric place of A's knight respect to the divider line ( also new 2 pieces can't threat each other ), so B is the winner !