Solve Chess Brain Teaser: White Mates in How Many Moves?

[RandallB]

Chess Brain Teaser

Clearly the two players here have been moving foolishly in the play of this game so far.
But from this point on, with white to move next, each side is to play to win or avoid the loss.
White mates in how many moves.
You must know and follow the rules of chess to logically figure this one out.
So at first just give the number of moves without explaining the solution when you get it.
NOTE: To see attached diagram it’s sometimes necessary to log out (Return to previously viewing) for the image to be viewable. Copy it and log in again.

http://www.apronus.com/chess/
to make chess diagrams online

 

[berkeman]

Well, PF definitely won't let me see it. What's the trick you're describing to see it? Log out, copy something and log in?

 

[20questions]

Hidden text (not a solution but thoughts/questions/spoilers!) are Black King / Queen reversed on purpose? second thought, K/Q switch can't 'legally' happen but board could be 'legal' if black's side is really on the bottom i.e. all pieces somehow switched board sides

 

[davee123]

Clearly the two players here have been moving foolishly in the play of this game so far.

It appears they also were pretty foolish in setting up the board, since somehow the black king and queen reversed themselves. Or, for the sake of argument, is black => white and white => black, meaning that white reversed its king and queen? Is this intentional and necessary for the solution to be relevant? Or is it assumed that the Kings and Queens line up as per usual?

DaveE

 

[mattmns]

Here is a link to the attachment, I hate having to log out

http://img371.imageshack.us/img371/8311/chessproblem3ij.jpg

 

[berkeman]

It appears they also were pretty foolish in setting up the board, since somehow the black king and queen reversed themselves. Or, for the sake of argument, is black => white and white => black, meaning that white reversed its king and queen? Is this intentional and necessary for the solution to be relevant? Or is it assumed that the Kings and Queens line up as per usual?
DaveE

Yeah, the board's set up wrong. It's physically impossible to get the black pieces in that arrangement with legal moves. It's even impossible for a corrected black arrangement to occur, since something had to take all the white pawns. Dumb puzzle.

 

[Greg825]

ok nevermind completely

 

[20questions]

There is an answer , if you read the hidden text in my last note the road to the solution will be revealed! Oh, I get 4

 

[RandallB]

Yeah, the board's set up wrong. It's physically impossible to get the black pieces in that arrangement with legal moves. It's even impossible for a corrected black arrangement to occur, since something had to take all the white pawns. Dumb puzzle.

INCORRECT
But your on the right track.
As stated in the problem the players didn't get into this position by playing to win!
However foolishly they moved the pieces or why, they moved them within the rules!
I know 20questions with a correct answer to the number of moves to checkmate understands how to move the black Queen to a white square yet have all the black pawns on a single rank.
Good job. 20questions.
Yet them think a bit more before explaining it.

 

[Greg825]

edit: arrrgh, the one google image of a chessboard I looked at mislead me.

 

[Greg825]

aaaaah, I think I see what happened! now to figure out the number of moves.

[color=#blacke]yea I get 4[/color]


Great puzzle randal

 

[berkeman]

INCORRECT
But your on the right track.
As stated in the problem the players didn't get into this position by playing to win!
However foolishly they moved they pieces or why they moved them within the rules!
I know 20questions with a correct answer to the number of moves to checkmate understands how to move the black Queen to a white square yet have all the black pawns on a single rank.
Good job. 20questions.
Yet them think a bit more before explaining it.

You sure? Maybe the knights could jump out and take all the other pawns and jump back, but how the heck did the king and queen get swapped? Is that a mistake but the rest is correct?

 

[neurocomp2003]

lol they switched sides like that ...pretty funny

 

[Jimmy Snyder]

Mate in 4:
1. Nc6, Nf3
2. Nb4, Ne5
3. Qxe5, any
4. Nd3 mate

 

[berkeman]

Mate in 4:
1. Nc6, Nf3
2. Nb4, Ne5
3. Qxe5, any
4. Nd3 mate

But that's not forced -- seems easy to avoid. And why are you moving black first?

 

[Jimmy Snyder]

why are you moving black first?

I'm not, the board is upside down.

 

[RandallB]

but how the heck did the king and queen get swapped?

That of course is the Key to the logic of figuring this brain teaser.
Good job for those with 4 as the correct answers.
The chess part is easy once you break the logic.

For those that haven’t seen this yet and may want to work on themselves I’ll leave the solution in white. (for those new to using white-out see the TOP sticky threads)

How did they move that Queen:
Impossible without moving a pawn!
Therefore a black pawn was moved.
But we most move all black pawns to a single rank!
Therefore these pawns must be on the 7th rank
and therefore we are viewing the board from black’s side of the board!
Once we are 'outside the box' the rest is easy chess.

 

[berkeman]

I'm not, the board is upside down.

Okay, with Randall's hint I finally see the reversal part. Fine. But your 4-move mate is totally unforced. Why would black move a knight right where you can take it to help double up your attack? Given your first move, black has lots of defenses. Is there a mate in 4 sequence that takes into account all the defenses?

 

[20questions]

Okay, with Randall's hint I finally see the reversal part. Fine. But your 4-move mate is totally unforced. Why would black move a knight right where you can take it to help double up your attack? Given your first move, black has lots of defenses. Is there a mate in 4 sequence that takes into account all the defenses?

hidden text: Black can only move either of his two knights, all his pawns are blocked from moving from the 7th row up to the 8th row by black's pieces, only the knights can jump over the pawns. White's knight can mate in 3 moves, black cannot free any other piece in time so can choose only to delay mate one move

 

[Jimmy Snyder]

Given your first move, black has lots of defenses.

For example?

 

[neurocomp2003]

mmm why doesn't black move a pawn to get a Queen? you have 4 moves...black can get a queen in 2-3 moves depending on if black wants a bishop or knight position queen. Black can check with black bishop and get queen in 3 moves to have doublesided queens

 

[Greg825]

mmm why doesn't black move a pawn to get a Queen? you have 4 moves...black can get a queen in 2-3 moves depending on if black wants a bishop or knight position queen. Black can check with black bishop and get queen in 3 moves to have doublesided queens

It looks to me like there isn't enough time. White can mate in 3 moves unless black defends with another knight move giving black only 2 moves. He can get a queen but can't move it anywhere in time.

 

[neurocomp2003]

GREG: what moves would you make to force blacks hand? because it seemes to me that black can make either a Defensive or offensive move and still get a queen in 2 moves.

 

[berkeman]

For example?

Oh jeeze Louise. 20Questions showed me my brain freeze. Dang, this board reversal part is obnoxious. Okay, the mate in 4 probably works. I'm too used to regular chess puzzles...

 

[Greg825]

GREG: what moves would you make to force blacks hand? because it seemes to me that black can make either a Defensive or offensive move and still get a queen in 2 moves.

I'm not good with chess notation but white can move his g knight to checkmate on white's third move. Black will have a queen right befor that but it won't do any good. (still on the 8th rank (or 1st?))

 

[neurocomp2003]

how do you get a N checkmate on move 3?

 

[Jimmy Snyder]

black can make either a Defensive or offensive move and still get a queen in 2 moves.

For example?

1. Nc6, Nf3
2. Nb4, g1=Q
3. Nd3 mate

 

[neurocomp2003]

ah ok...i see

first aren't you attacking the queen...i thought the spiky head peace is the queen...2ndly why do you assume black moves N inside not out to guard against it...and thus white would need to sacrifice a move by taking the N with a rook...whereby black will have queened on the next move...and checked on his 3rd move.