White to move and mate in two.

December 11, 2006 7:53 AM

Help me solve a chess problem, please?

Can you tell me the solution to the first chess problem displayed on this page (the one labeled "From 'Award-Winning Chess Problems' (no.1) I.V.Diaconu, Der Waarheid 1967")? A few friends and I have been puzzling over it for a couple days, but we're stumped. We're no chess masters, but we're pretty good with google... and still no solution. I'm admitting defeat, but I still want to know how it works! Thanks.

posted by vytae to Sports, Hobbies, & Recreation (33 answers total)

I'm a chess n00b, but here is my guess:

White moves the Queen to b1. Then the next move, the Queen moves to g1 and takes the rook.

Does that work?

Warning: as disclaimed, I know little about chess.
posted by dios at 8:05 AM on December 11, 2006

dios's solution works unless the black king moves to h2 after white's first move. Then it would be mate in 3 (if black queen moved to h1).
posted by JeremiahBritt at 8:10 AM on December 11, 2006

Eh, that's not the solution.

Doh! Let me look again and actually think this time.
posted by dios at 8:10 AM on December 11, 2006

I'm glad you understood that, because I messed up the colors.
posted by JeremiahBritt at 8:24 AM on December 11, 2006

I think the solution is Queen to a7.

If pawn to f3, Queen takes bishop on g1 checkmate.

If bishop to h2, Knight takes f2 checkmate.

If king to h2, Queen to h7 checkmate.
posted by ducksauce at 8:25 AM on December 11, 2006

Best answer: 3 senarios:

Qb2
f3
Qg2++

or

Qb2
Bh3
Kf2++

or

Qb2
King to h2
Qh8++

I forget notation, but I think that's easy enough to understand.
posted by cowbellemoo at 8:27 AM on December 11, 2006

By the way, if you enjoyed this struggle, you might want to check out these two books, which I've been working my way through very slowly.
posted by ducksauce at 8:28 AM on December 11, 2006

Good call ducksauce.
posted by dios at 8:28 AM on December 11, 2006

queen to a7...
if black queens the pawn, knight to g3 mate...
if black moves the bishop to h2, knight takes pawn mate...
if black moves king to h2, queen to h7 mate.
posted by bruce at 8:37 AM on December 11, 2006

and if black underpromotes the pawn to a knight, then queen takes bishop mate.
posted by bruce at 8:40 AM on December 11, 2006

disregard previous answer. buhhhh!
posted by bruce at 8:53 AM on December 11, 2006

Best answer: Oh... I completely missed that black and white were heading in their typical directions on the board because the position was so weird.

I think the answer is Qb2. bruce, if 1.Qa7 f8=Q then 2. Ng3 kh2.

If the white Queen is on b2 then the king is trapped and Ng3 is checkmate, as you said.

So:
1. Qb2

If 1 ... f8=Q or R 2. Ng3 checkmate.

If 1 ... f8=N or B 2. Qg2 checkmate.

The other circumstances are as cowbellemoo said.
posted by ducksauce at 8:53 AM on December 11, 2006

Response by poster: Oh wait, how do we know which direction the pieces are supposed to be moving? I assumed that black pawn was in its starting position.
posted by vytae at 8:57 AM on December 11, 2006

Typically in chess problems the black pieces start at the top and the white pieces start at the bottom, so all positions are from white's starting perspective.
posted by ducksauce at 8:59 AM on December 11, 2006

Black is about to promote the pawn on f2.
Qb2 seems the way to go.
posted by bastionofsanity at 9:06 AM on December 11, 2006

Response by poster: ducksauce:
This notation is all new to me, but I think I'm mostly getting it. So if "1 ... f8=B" means that the pawn gets promoted to a bishop, wouldn't Qg2 then allow the new bishop to take the queen, instead of giving check-mate? But then maybe you could just use Ng3 instead of Qg2 if the pawn is promoted to a bishop. Does that make sense?
posted by vytae at 9:28 AM on December 11, 2006

Oh heh.. I messed the direction up, too. Good to know I'll still win that game, though!
posted by cowbellemoo at 9:28 AM on December 11, 2006

In case you have more you need help with, computer chess programs--some of which are free--can generally solve mate-in-n puzzles.
posted by DevilsAdvocate at 9:39 AM on December 11, 2006

vytae, yeah -- I became disoriented once again -- this time in text layout. =) The "R" and "B" were, as you found, misplaced in my answer. Should have been:

If 1 ... f8=Q or B 2. Ng3 checkmate.

If 1 ... f8=N or R 2. Qg2 checkmate.
posted by ducksauce at 10:30 AM on December 11, 2006

I dont really know the notation either, but wouldnt it be

If 1 ... f1=Q or B 2. Ng3 checkmate.

If 1 ... f1=N or R 2. Qg2 checkmate.

Since the pawn is on f2 now? Or am I missing something.
posted by skrike at 10:57 AM on December 11, 2006

phalanx (an open-source chess engine) gives Qb8-b2 Mate in 2 when presented with the board in question.
posted by jepler at 11:27 AM on December 11, 2006

Bastionofsanity is correct. Most of you have the wrong direction for black's pawn. The pawn is moving down the board, and is about ready to be promoted. It cannot capture up the board.

That said, I don't have an answer.
posted by jdroth at 12:29 PM on December 11, 2006

ok so why not Queen to b1?
Black from that position must move the pawn or the king:

If he promotes kill whatever gets promoted, the king is forced to move to h2, queen to g2 and mate.

If he moves the King out to h2 then move the Queen to f1 forcing the king back to corner (no other move to make). Queen to g2 and mate.

Or was that 3 moves instead of 2? The way I understand the problem is that white has a move and then will mate on 2 additional moves.
posted by Numenorian at 1:18 PM on December 11, 2006

That's three moves, Numenorian. "White to move and mate in two" means that White must deliver mate on his second move. (I can see that the description might be confusing to one not familiar with the conventions of chess problems, but that's the convention nonetheless.)
posted by DevilsAdvocate at 1:38 PM on December 11, 2006

Best answer: Here's what I've come up with, by distilling everyone's comments above. Does anybody see any problems with this?

Start by moving the queen to b2.
Then the second step depends on black's next move:

black king to h2 -> white queen to h8 for checkmate

black bishop to h2 -> white knight takes pawn on f2 for checkmate

black pawn to f1 and thus promoted to queen, rook, or bishop -> white knight to g3 for checkmate

black pawn to f1 and promoted to knight -> queen to g2 for checkmate

Does this work?
posted by vytae at 1:49 PM on December 11, 2006

White first plays Q to B7
if black's interceding move is to block the threatened mate of Q to H7 then white plays N x P for mate.

I can't believe I'm the first answer in the thread to get this!
posted by spock at 10:19 PM on December 11, 2006

I should have said "if black's interceding move is to block the threatened mate of Q to H7 (with B to H2) then white plays N x P for mate."
posted by spock at 10:21 PM on December 11, 2006

Response by poster: spock, if black responds to your first move by moving pawn to f4, then you have no way to get mate on your next move. Even if you move Q to H7, black could move his bishop to h2 to block it. Q to B7 doesn't guarantee mate in two, it requires that black make a specific error, so it doesn't count as a solution to this particular problem.
posted by vytae at 7:11 AM on December 12, 2006

vytae, Black cannot respond 1... f4 because the black pawn is moving down the board.

spock, 1. Qb7 fails after 1... f1=any. If 2. Qh7+, 2... Bh2 (or 2... Qh3 or 2... Bh3 or 2... Nh2 if the pawn was promoted to one of those pieces.)
posted by DevilsAdvocate at 8:54 AM on December 12, 2006

Response by poster: Ack, you're right DA... Just when I thought I had gotten over my confusion! Sorry.

Can anybody confirm or deny the summary I posted above? I think I was less confused when I wrote that.
posted by vytae at 9:06 AM on December 12, 2006

The summary looks correct to me, vytae. (Credentials: ~1600 USCF rating. Which is by no means anywhere near a master, but is better than most casual players.)
posted by DevilsAdvocate at 9:15 AM on December 12, 2006

Vytae has the answer. I see why I didn't see it before when everyone was mentioning b2 as I didn't see the move to h8 because it's been awhile and I must be spaitially retarded.
posted by Numenorian at 9:26 AM on December 12, 2006

Response by poster: OK, it feels really weird to mark myself as best answer, but hopefully that'll help any future searchers who stumble upon this thread. I've also marked the comments that I used to create my summary. Thanks to all of you!
posted by vytae at 11:26 AM on December 12, 2006