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Comments on Puzzle #24070: 25 Queens
By Joe (infrapinklizzard)

peek at solution       solve puzzle
  quality:   difficulty:   solvability: line & color logic only  

Puzzle Description:

In this puzzle, there are no overlapping colors in any of the rows, columns, or 45° diagonals.

#1: Joe (infrapinklizzard) on Mar 22, 2014 [SPOILER]

I decided to play with the concept in #6435: "32 Queens" http://webpbn.com/6435 and especially in its comment #7. Specifically, I decided to see what would happen if you applied a "no diagonal" rule while also adding that ALL squares must be covered by a queen.

This has rotational symmetry, with each of four colors making a chair-like shape with its "back" going into a corner. (E.g. the red chair is leaning back against the right wall.) The fifth color (white) makes a five-pip shape.

I'm pretty sure there is no way to have each square be covered by a queen and fulfill the requirements above without it being symmetrical.

I also think that you cannot have all squares covered by queens and fulfill the above requirements while having a board that has dimensions that do not have a prime factor >2 (eg. 2x2, 4x4, 8x8 etc; but 6x6 would work as it has a prime factor of 3).
#2: Joe (infrapinklizzard) on Mar 24, 2014 [SPOILER]
And I have found a 6x6 that works. It has rotational symmetry. Four colors have one pattern and two another.

I'm not sure I have the patience to prove my 8x8 hypothesis through brute force.
#3: Thomas Genuine (Genuine) on Mar 24, 2014
Wow! SudokuX without numbers! Incredilble! :)
#4: Jota (jota) on Mar 24, 2014
Fun!
#5: Norma Dee (norm0908) on Mar 24, 2014
Neat. Brings to mind latin squares which I studied in some ancient time period.

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