Trap the Knight Brainteaser

[Otis]

A chess knight sits on an infinite chessboard. If the knight cannot revisit a square previously occupied, then how can one trap it in as few moves as possible?



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[Otis]

Spoiler

I got 15 moves, on my first attempt. I'm trying to shorten that…

EDIT: Originally, I had 13 moves, but I'd messed up.

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[lev888]

A chess knight sits on an infinite chessboard. If the knight cannot revisit a square previously occupied, then how can one trap it in as few moves as possible?



[imath]\;[/imath]

Trap with which piece(s)?

 

[Cubist]

Here's a board to aid thinking...

Trap with which piece(s)?

I think the knight is the only piece on the board and the goal is to trap it by having previously occupied all the squares that it might otherwise be able to move to (can only visit a particular square once)

 

[lev888]

Here's a board to aid thinking...

View attachment 32095


I think the knight is the only piece on the board and the goal is to trap it by having previously occupied all the squares that it might otherwise be able to move to (can only visit a particular square once)

Thanks. I think in this case the question should've been "how can the knight trap itself".

 

[Cubist]

Spoiler: my best number of moves

I got 15 moves

Spoiler: reveal my solution

Start at the spot and end up on the green square. The knight is then trapped because it can't re-visit the surrounding red squares.

 

[Otis]

Trap with which piece(s)?

There are no other pieces, Lev. (The brainteaser is not part of a chess game.)

By "trap", I mean moving the Knight until it cannot move any more.

should've been "how can the knight trap itself".

Could've been, yes, if the knight were to move itself.

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[Otis]

Oops, I'd goofed up my scratch work. I also get 15.

?

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