Comments on: White to move and mate in two.

Question: White to move and mate in two.

vytae — Mon, 11 Dec 2006 07:53:55 -0800

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.

By: dios

dios — Mon, 11 Dec 2006 08:05:13 -0800

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.

By: JeremiahBritt

JeremiahBritt — Mon, 11 Dec 2006 08:10:34 -0800

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).

By: dios

dios — Mon, 11 Dec 2006 08:10:47 -0800

Eh, that's not the solution.

Doh! Let me look again and actually think this time.

By: JeremiahBritt

JeremiahBritt — Mon, 11 Dec 2006 08:24:28 -0800

I'm glad you understood that, because I messed up the colors.

By: ducksauce

ducksauce — Mon, 11 Dec 2006 08:25:18 -0800

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.

By: cowbellemoo

cowbellemoo — Mon, 11 Dec 2006 08:27:12 -0800

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.

By: ducksauce

ducksauce — Mon, 11 Dec 2006 08:28:38 -0800

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.

By: dios

dios — Mon, 11 Dec 2006 08:28:56 -0800

Good call ducksauce.

By: bruce

bruce — Mon, 11 Dec 2006 08:37:54 -0800

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.

By: bruce

bruce — Mon, 11 Dec 2006 08:40:50 -0800

and if black underpromotes the pawn to a knight, then queen takes bishop mate.

By: bruce

bruce — Mon, 11 Dec 2006 08:53:20 -0800

disregard previous answer. buhhhh!

By: ducksauce

ducksauce — Mon, 11 Dec 2006 08:53:51 -0800

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.

By: vytae

vytae — Mon, 11 Dec 2006 08:57:43 -0800

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.

By: ducksauce

ducksauce — Mon, 11 Dec 2006 08:59:06 -0800

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.

By: bastionofsanity

bastionofsanity — Mon, 11 Dec 2006 09:06:03 -0800

Black is about to promote the pawn on f2.
Qb2 seems the way to go.

By: vytae

vytae — Mon, 11 Dec 2006 09:28:25 -0800

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?

By: cowbellemoo

cowbellemoo — Mon, 11 Dec 2006 09:28:57 -0800

Oh heh.. I messed the direction up, too. Good to know I'll still win that game, though!

By: DevilsAdvocate

DevilsAdvocate — Mon, 11 Dec 2006 09:39:42 -0800

In case you have more you need help with, computer chess programs--some of which are free--can generally solve mate-in-n puzzles.

By: ducksauce

ducksauce — Mon, 11 Dec 2006 10:30:47 -0800

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.

By: skrike

skrike — Mon, 11 Dec 2006 10:57:17 -0800

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.

By: jepler

jepler — Mon, 11 Dec 2006 11:27:17 -0800

phalanx (an open-source chess engine) gives Qb8-b2 Mate in 2 when presented with the board in question.

By: jdroth

jdroth — Mon, 11 Dec 2006 12:29:07 -0800

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.

By: Numenorian

Numenorian — Mon, 11 Dec 2006 13:18:52 -0800

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.

By: DevilsAdvocate

DevilsAdvocate — Mon, 11 Dec 2006 13:38:00 -0800

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.)

By: vytae

vytae — Mon, 11 Dec 2006 13:49:57 -0800

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?

By: spock

spock — Mon, 11 Dec 2006 22:19:33 -0800

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!

By: spock

spock — Mon, 11 Dec 2006 22:21:23 -0800

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."

By: vytae

vytae — Tue, 12 Dec 2006 07:11:50 -0800

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.

By: DevilsAdvocate

DevilsAdvocate — Tue, 12 Dec 2006 08:54:18 -0800

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.)

By: vytae

vytae — Tue, 12 Dec 2006 09:06:15 -0800

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.

By: DevilsAdvocate

DevilsAdvocate — Tue, 12 Dec 2006 09:15:44 -0800

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.)

By: Numenorian

Numenorian — Tue, 12 Dec 2006 09:26:44 -0800

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.

By: vytae

vytae — Tue, 12 Dec 2006 11:26:49 -0800

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!