Cutting apart a chessboard

Cutting apart a chessboard

Posers and Puzzles

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Art, not a Toil

60.13N / 25.01E

Joined
19 Sep 11
Moves
56972
27 Oct 11

Not that any of us would do such a thing, but if we did, and wanted to cut it to 64 separate squares, how many cuts would it take? A single cut goes between any two rows or columns to the other end, cutting the board or part thereof in two. For example the first cut could be between the columns e and f, making two rectangles, A1-E8 and F1-H8. The second would cut one of the pieces in two, so you might end up with, say, A1-E8, F1-H6 and F7-H8. That procedure would be continued until all 64 squares are separate.

f
Defend the Universe

127.0.0.1

Joined
18 Dec 03
Moves
16687
27 Oct 11
1 edit

I get the same answer for each attempt I have tried.

63


It makes sense, since no cut can cross another cut.

Art, not a Toil

60.13N / 25.01E

Joined
19 Sep 11
Moves
56972
27 Oct 11

Perfect sense indeed, as each cut, regardless of whether it splits off one square or many, increases the number of pieces by one. 🙂

a

.

Joined
06 Feb 10
Moves
6916
28 Oct 11
1 edit

And if the cuts didn't have to be straight (but still followed the edges of the squares) then the number would be considerably less.

f
Defend the Universe

127.0.0.1

Joined
18 Dec 03
Moves
16687
28 Oct 11

I don't think so.

You can still increase the total number of pieces by only one.

Art, not a Toil

60.13N / 25.01E

Joined
19 Sep 11
Moves
56972
28 Oct 11
1 edit

Agreed. If a "cut" ends when a piece of the board is falls into two pieces, n - 1 is how many it takes where n is the number of pieces. Of course, if a cut is defined differently, a whole new problem is found. If a cut is a line that follows goes between the squares, ending at an intersection from which there are no routes out.. it could be doable with as few as

fourteen
?

a

.

Joined
06 Feb 10
Moves
6916
28 Oct 11

Agreed it comes down to the definition of a cut. When I made my earlier statement I didn't define the separation of the board into 2 pieces as a complete cut - I envisaged cutting from one edge of the original board to another edge following a diagonal / stepped path but not turning back on a previous direction. Visualise cutting steps into the board starting at one corner. I also came up with 14.

Joined
26 Apr 03
Moves
26771
30 Oct 11

Interesting 14 is also the answer if the straight cuts can cross previous cuts (without rearranging)

Art, not a Toil

60.13N / 25.01E

Joined
19 Sep 11
Moves
56972
30 Oct 11

Not a coincidence. Every intersection on the board has four lines leading into it, so no cut can end there if none starts there. That leaves 7 end points on each side of the board, 4 x 7 = 28; each cut removes 2 of them; 28 : 2 = 14.