You have 10 seconds to tell me....

...the number of Knights you can place on a chessboard
without any of the Knights being able to take each other.

This was a question on QI XL tonight.

Answer

Reveal Hidden Content

Love that show 🙂

The episode this puzzle is from is quite fittingly called 'Knights and Knaves',
here's a link to watch it:
YouTube

And quite happily, I knew the answer within 10 seconds 😀

Nice puzzle! I feel it teaches something about the value of knights versus the other pieces.

Compare these numbers:
- 32 knights can be placed without interference
- 14 bishops: 7 light + 7 dark (please check this number, but I'm quite certain)
- 8 rooks
- 8 queens

Hi tvochess,



What about the Kings? How many Kings can you place on a board
without them attacking each other.

The Knight is the only piece restriced to where it moves. It's move never
changes. It always has a pre-determinded destination which can range from
eight to two squares depending where on the board it is placed.

Even the King can castle and pawns take different from the way they move.

The Rook on a clear board is the only piece not restricted by the corners
or the a & h-files. No matter where you place it, it will always control 14 squares.

Question 2.

Blindfold yourself and using a genuine Staunton Set design take out one
White Rook, One Black Rook, One White Knight and One Black Knight.
How can you do this without making a mistake? (for intance removing
two Black Rooks.)

The time for this one is 2 seconds. You either know this or you don't.

Originally posted by greenpawn34
What about the Kings? How many Kings can you place on a board
without them attacking each other.

At least Reveal Hidden Content. It may be possible to add more by using a fishbone pattern, but I don't think it is.

Question 2.

Blindfold yourself and using a genuine Staunton Set design take out one
White Rook, One Black Rook, One White Knight and One Black Knight.
How can you do this without making a mistake? (for intance removing
two Black Rooks.)

In my case, simply by taking one each from the left hand box and one from the right. I presume you have a solution for when they're all on one box, where officially the ears and crenellations are notched differently, but I don't have an official match set at hand so I don't know.

Question 2.

Blindfold yourself and using a genuine Staunton Set design take out one
White Rook, One Black Rook, One White Knight and One Black Knight.
How can you do this without making a mistake? (for intance removing
two Black Rooks.)

The time for this one is 2 seconds. You either know this or you don't.[/b]

Assuming that the pieces are correctly placed on the board, then remove the first two pieces from the top rank left and the two pieces from the bottom rank left. ( Top and bottom ranks right will achieve the same result ) They will be the Rook and Knight - colour selection is not a factor as they will be at opposite ends of the board and therefore of opposite colour.

Originally posted by greenpawn34
Hi tvochess,

[fen]1N1N1N1N/N1N1N1N1/1N1N1N1N/N1N1N1N1/1N1N1N1N/N1N1N1N1/1N1N1N1N/N1N1N1N1 w - - 0 1[/fen]

What about the Kings? How many Kings can you place on a board
without them attacking each other.

The Knight is the only piece restriced to where it moves. It's move never
changes. It always has a pre-determinded destination which can ran ...[text shortened]... ing
two Black Rooks.)

The time for this one is 2 seconds. You either know this or you don't.

I would vote for 10, and if that be denied me, 64. Pieces of the same color do not attack each other.

On an original Staunton set a Rook and Knight of each colour have
a King symbol stamped into them. You can easily feel it.
It's on top of the Rook and on the Knight's forehead.

This is for notation purposes so you can tell the difference between
the King's Rook/Knight and the Queen's Rook/Knight.

Originally posted by greenpawn34
On an original Staunton set a Rook and Knight of each colour have
a King symbol stamped into them. You can easily feel it.
It's on top of the Rook and on the Knight's forehead.

This is for notation purposes so you can tell the difference between
the King's Rook/Knight and the Queen's Rook/Knight.

What if the rooks or knights have swapped place? In normal descriptive notation, AIUI (which is reluctantly!), the rook now on the queen's side is the QR, the one on the starboard side is the KR, not the one which started on that side. This is necessary, because you may well have to annotate a position for which you don't know the move history, or for which (in a problem, for example) there isn't one in the first place.

There's a more psychological reason to dislike such marking, too: it makes the player believe that there is a real, rather than merely positional, difference between the two equal pieces. That the King's Knight is somehow more active than the Queen's, who is more defensive - or v.v., it makes no difference. That way lies a rapid descent into madness.