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A puzzle involving checkerboards: grids of squares alternating black and white in color, most commonly an 8x8 board.

3 votes

Professor Halfbrain's infinite chessboard theorems

Theorem 1a is also true and it 'follows' from the previous result. Suppose we have colored our infinite chessboard blue and red, and suppose without loss of generality the red squares are not queen-co …
Fimpellizzeri's user avatar
12 votes

Professor Halfbrain's chessboard theorems

Adding to Joe Z.'s answer, the third theorem is also false. 2 1 1 3 1 3 1 2 1 1 3 2 3 2 2 1 The the bottom-right 1, the top-left 2 and the middle 3's (versus the outer 3's) are …
Fimpellizzeri's user avatar
10 votes
Accepted

Professor Halfbrain and the 9x9 chessboard (Part 2)

I've been thinking on this problem for a long time, and I think I nailed it. I will expand on the ideas I used for the solution of part 1 of this puzzle, and also on the reasoning of Michael Seifert's …
Fimpellizzeri's user avatar
16 votes
Accepted

Professor Halfbrain and the 9x9 chessboard (Part 1)

There is a simple way to see that manshu's answer $x=25$ is correct. Translate the problem into an easier problem: Rather than consider a $9\times 9$ board and pawns, consider a $10 \times 10$ board a …
Fimpellizzeri's user avatar
8 votes
Accepted

Concentrating tokens on an infinite board

Following in the footsteps of Big Black Box's and Trenin's answers, this shows very concretely that... I tried a lot of different approaches to this problem, but ultimately it's taking the courage …
Fimpellizzeri's user avatar