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        riddles >> medium >> Mate in 2
        
(Message started by: Lightboxes on Sep 20th, 2003, 8:10pm)
Title: Mate in 2
Post by Lightboxes on Sep 20th, 2003, 8:10pm
EEEAAAHHHHHH!
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 20th, 2003, 10:02pm
There is no standard mate-in-2 unless

a) White is playing down the board
OR
b) It is a helpmate

Also, Black had no legal previous move (although this is unimportant in mate puzzles).
Title: Re: Mate in 2
Post by Icarus on Sep 20th, 2003, 10:10pm
Well - I suffer the twin problems of being lousy at chess, and not knowing the standard conventions, but what is wrong with this: white brings his knight up to the right of his king. Black's king will be trapped in his corner, so his only move is to capture the rook with his pawn. Next white moves his bishop up to check the king.

It looks like it works to me.
Title: Re: Mate in 2
Post by william wu on Sep 20th, 2003, 11:04pm
Yeah, that works.


on 09/20/03 at 22:02:16, THUDandBLUNDER wrote:
Also, Black had no legal previous move (although this is unimportant in mate puzzles).


Couldn't black have had some other pieces which were then taken to get to this stage of the game?
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 21st, 2003, 12:39am

Quote:
white brings his knight up to the right of his king. Black's king will be trapped in his corner, so his only move is to capture the rook with his pawn.

That would be an unintentional helpmate.
Black can move his pawn two squares (P on f7 to f5) instead of capturing the rook. This prevents checkmate.


Quote:
Well - I suffer the twin problems of being lousy at chess, and not knowing the standard conventions,

Icarus, it's nice to know that if I ever want to stump you, all I have to do is post a mate-in-1 chess puzzle. http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_easy;action=display;num=1064157616;start=0  :D


Quote:
Couldn't black have had some other pieces which were then taken to get to this stage of the game?

It is White to move (presumably). So Black moved last. He hasn't moved his pawn and, while his king may otherwise have captured something on its last move, it has no square to move from because they are both attacked by the White king. But, as I said, I believe the illegal position is not relevant. As it's in Medium, there must be some trick. (I don't think it's worth posting boring run-of-the-mill mate-in-x-moves puzzles in this forum.)

I think I have it:
[hide] It is Black to move, not White. He plays P on f7 to f5 (or f6) in order to avoid the mate suggested by Icarus. White plays K to f2 (or Nf3) to avoid being checked by the Black pawn on the next move. Black is now forced to push his pawn again. And White then plays R to h6 mate. If that is it, I don't think it is Medium. [/hide]
Title: Re: Mate in 2
Post by Barukh on Sep 21st, 2003, 5:41am
I tend to agree with THUDandBLUNDER about the trick. Just being more specific about the possibilities:
[hide]
0. ... f6 1. Nh3 (1. Kf2? Kh2!)
0. ... f5 1. Kf2
0. ... f7:e6 1. Kf2
0. ... K:g1 1. Rf6
[/hide]
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 21st, 2003, 6:25am
I agree with you Barukh, except:
[hide]
If 0...f6, 1.Nf3 f5 and 2.Rh6 mate (not 1.Nh3? f5 and there is no mate next move).
If 0...fxe6, 1.Nh3 e5 2.Be4 mate (not 1.Kf2? Kh2 and there is no mate next move).
[/hide]
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 21st, 2003, 8:46am
Here's another mate-in-2 (should be in Easy):
Title: Re: Mate in 2
Post by Barukh on Sep 21st, 2003, 10:52am

on 09/21/03 at 06:25:25, THUDandBLUNDER wrote:
I agree with you Barukh, except: ...

Now, I agree with you THUDandBLUNDER, except:
[hide]
If 0...f6, 1.Nf3 f5 and 2.Rh6 mate - this doesn't work, rook cannot move to h6 through pawn at f6.
[/hide]
Title: Re: Mate in 2
Post by Icarus on Sep 21st, 2003, 11:20am

on 09/21/03 at 00:39:59, THUDandBLUNDER wrote:
Icarus, it's nice to know that if I ever want to stump you, all I have to do is post a mate-in-1 chess puzzle.


Nah... Those things don't stump me because I ignore them! ;)
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 21st, 2003, 10:27pm

Quote:
If 0...f6, 1.Nf3 f5 and 2.Rh6 mate - this doesn't work, rook cannot move to h6 through pawn at f6.

A pawn which has moved to f5! (1.Nf3 f5)
Title: Re: Mate in 2
Post by Barukh on Sep 22nd, 2003, 2:01am

on 09/21/03 at 22:27:09, THUDandBLUNDER wrote:
A pawn which has moved to f5! (1.Nf3 f5)

Ooops...  :-/
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 22nd, 2003, 5:04am
Checkmate in 2 moves.

(The last puzzle I posted in this thread is still unsolved.)
Title: Re: Mate in 2
Post by Sir Col on Sep 22nd, 2003, 5:43am
Solution to previous puzzle...
::[hide]
White plays Qc6, check.

Black can play one of two moves:
(i) Kd8, followed by White Qd7, mate.
(ii) Kf8, followed by White Qa8, mate.
[/hide]::

I'm still not 100% sure how to use this notation, so I hope that makes sense?

For the last puzzle...
::[hide]
White plays Ra7.

Whatever black plays, white then plays Ra8, mate.
[/hide]::
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 22nd, 2003, 6:03am

Quote:
(ii) Kf8, followed by White Qa8, mate.

From f8 Black can move to g7.


Quote:
White plays Ra7. Whatever black plays, white then plays Ra8, mate.

Did you consider 0-0 (Black castles kingside)?
Title: Re: Mate in 2
Post by Sir Col on Sep 22nd, 2003, 6:13am
No!   :'(

I think I should stick with Easy puzzles before I progress to these big boy puzzles. :-[
Title: Re: Mate in 2
Post by wowbagger on Sep 22nd, 2003, 6:30am
[quote author=Sir Col link=board=riddles_medium;num=1064113854;start=0#15 date=09/22/03 at 06:13:11]I think I should stick with Easy puzzles before I progress to these big boy puzzles. :-[/quote]
At least you can increase your post count - unlike me. ;)
I saw the problem with your solutions to T&B's puzzles, so I didn't post. Unfortunately, I also found a problem with my first idea for his first problem ([hide]1. Qa3[/hide]), so I'll have to spend more thought on this one sometime.
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 22nd, 2003, 6:56am

Quote:
I think I should stick with Easy puzzles before I progress to these big boy puzzles.

The first one belongs in Easy. I only posted it in this thread because it's a Mate in 2.

The second one could be described as Medium, but only just.

Title: Re: Mate in 2
Post by Lightboxes on Sep 22nd, 2003, 7:47am
For the first one
::[hide]Q goes to the bottom left hand corner...
the rest is self explantory except maybe the fact that black can not castle because white is moving which means black has moved last which means he must have moved a piece (the king or rook).
[/hide]::::
Title: Re: Mate in 2
Post by Lightboxes on Sep 22nd, 2003, 8:20am
For the second one I've eliminated these general options:
***White sacrificing himself to force a move.
***White playing down the board.
***Black could still castle even if he played last because of his pawn at b6.
***White keeping black from castling because it would take 3 moves and even then, black can stop white at a5.  

So if anyone think of something else like white has one teleportation move that black already used...?
So basically, I'm saying that I'm stumped.
Title: Re: Mate in 2
Post by Sir Col on Sep 22nd, 2003, 8:31am

on 09/22/03 at 06:56:24, THUDandBLUNDER wrote:
The first one belongs in Easy. I only posted it in this thread because it's a Mate in 2.

Thanks! In which case I think we need a new area: Really Easy.  :P

Lightboxes, I don't see how the queen moving to a1 will help? What if the black moves Kd8? In addition, nothing says it is white's move next, so black could castle on the next move.
Title: Re: Mate in 2
Post by wowbagger on Sep 22nd, 2003, 8:41am

on 09/22/03 at 08:31:08, Sir Col wrote:
Thanks! In which case I think we need a new area: Really Easy.  :P

Lightboxes, I don't see how the queen moving to a1 will help? What if the black moves Kd8?

2. [hide]Qh8 checkmate[/hide]
Lightboxes's solution is correct. And I'd say it's easy (although I didn't see it at first glance).


Quote:
In addition, nothing says it is white's move next, so black could castle on the next move.

If it's Black's move, he can't castle because he'd illegally castle into check (c8 is under control of the White queen).
If it's White's move, Black's last move must have been with his king or rook, so he can't castle anymore.
Title: Re: Mate in 2
Post by wowbagger on Sep 22nd, 2003, 8:54am

on 09/22/03 at 08:20:56, Lightboxes wrote:
So if anyone think of something else like white has one teleportation move that black already used...?
So basically, I'm saying that I'm stumped.

I was going to say that I was stumped, too. But I just noticed something I hadn't thought about before: Black's [hide]kingside bishop is missing. Considering the possibilities that could have happened, we can rule out the bishop moving (e7, g7 still in place). However, a knight could have captured on f8 without the Black king or rook having to move. Or even the White queen could have captured the Black bishop before being captured herself by the Black queen.[/hide]
I'm not sure whether this is of much help, but maybe we can somehow deduce that Black must have lost his right to castle. :-/
Title: Re: Mate in 2
Post by Sir Col on Sep 22nd, 2003, 9:05am

on 09/22/03 at 08:41:52, wowbagger wrote:
2. [hide]Qh8 checkmate[/hide]
Lightboxes's solution is correct. And I'd say it's easy (although I didn't see it at first glance).

If it's Black's move, he can't castle because he'd illegally castle into check (c8 is under control of the White queen).
If it's White's move, Black's last move must have been with his king or rook, so he can't castle anymore.

Thanks for explaining, wowbagger. I just couldn't see that checkmate.

Nice moves, Lightboxes!
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 22nd, 2003, 9:19am
Perhaps a hint is required:
[hide]A move is considered legal unless it can be proved that it is illegal. [/hide]

Not much of a hint, I know, but it's important here.  
Title: Re: Mate in 2
Post by Lightboxes on Sep 22nd, 2003, 9:25am
I hope you don't mean the black bishop, will help, that would have been captured at home?
Title: Re: Mate in 2
Post by wowbagger on Sep 22nd, 2003, 9:32am

on 09/22/03 at 09:25:54, Lightboxes wrote:
I hope you don't mean the black bishop, will help, that would have been captured at home?

Are you asking T&B or me? I was thinking it might help, but I don't see how.
Title: Re: Mate in 2
Post by Lightboxes on Sep 22nd, 2003, 10:07am
FINALLY!!!!!
I feel so proud of myself but too bad I can't take all the credit because of THUDandBLUNDER's hint. I'm actually in class right now...I ran to a computer lab after I yelled in class, "yes!".
::[hide]Assume white AND black can castle.  Then this means a rook did not get out from the right hand corner but was rather promoted by a pawn.  Can a rook get out of blacks defense without disturbing black's castling opportunities?  Simple, either the rook moved or the king did to let out the white rook from behind enemy lines.  Therefore, black can NOT castle.  MWHAHAHHA.  I'm not a quiter after all.  :)
So the solution, previously stated is correct, a1 - a7, and black can not do a thing to stop the next move at a7 - a8.
[/hide]::
Title: Re: Mate in 2
Post by wowbagger on Sep 22nd, 2003, 10:23am

on 09/22/03 at 10:07:15, Lightboxes wrote:
FINALLY!!!!!
I feel so proud of myself but too bad I can't take all the credit because of THUDandBLUNDER's hint.

Very nice, Lightboxes! And you shouldn't hide your light under a bushel just because of that very general remark of T&B. After all, he said it isn't much of a hint himself.


Quote:
I'm actually in class right now...I ran to a computer lab after I yelled in class, "yes!".

;D ;D

T&B, somehow I don't like the reasoning in this one. (I bet you saw that coming. :D)
Can't we argue that Black still has the option to castle to the kingside because it can't be proved to be illegal? It's possible that it is illegal, of course, but we can't prove it, can we? The position could occur with White still allowed to castle, but it also without this option.
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 22nd, 2003, 10:29am
Don't start the party yet, Lightboxes.   ;D

What if the rook on d4 came from a1 or h1?


Quote:
T&B, somehow I don't like the reasoning in this one.

That does not surprise me.  :D  The reasoning is incomplete.
Title: Re: Mate in 2
Post by Lightboxes on Sep 22nd, 2003, 1:57pm
I had to modify this a few times to make it clear.
::
[hide]The WHITE rook at h1 died in that area BECAUSE white can still castle.  The WHITE rook at d4 was promoted by a pawn.

But the WHITE rook at d4, has to be right next to the BLACK king to get out OR in the exact place of the BLACK rook at the top right.  In other words, the black king or black rook has to move to allow the WHITE rook to get out!  One reason is because of check.  The other reason because two rooks can't occupy the same space at the same time.  Therefore, Black had to move his BLACK king or BLACK rook.  Now he can't castle.
[/hide]
::
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 22nd, 2003, 7:50pm
Sorry, Lightboxes, but you have not proved that Black cannot castle.
The reasoning you give is pefectly correct as far as it goes. But it is incomplete.

Hence your solution of 1. Rxa7 is wrong.   :(
Title: Re: Mate in 2
Post by Lightboxes on Sep 22nd, 2003, 8:17pm
INCOMPLETE!  I can't think of anything to add you crazy old man! (my g/f calls me this sometimes so don't feel offended)
EEEAAAHHHHHH!
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 22nd, 2003, 8:39pm

Quote:
The WHITE rook at h1 died in that area BECAUSE white can still castle.  The WHITE rook at d4 was promoted by a pawn.

Briefly, why do you believe that White can still castle?


Quote:
I can't think of anything to add you crazy old man! (my g/f calls me this sometimes...)

She must be jail-bait. If you can't be good, be careful.  :D
Title: Re: Mate in 2
Post by Lightboxes on Sep 22nd, 2003, 9:12pm
The only thing I can say is that the only way I see a solution to the mate in 2 is if white can castle.  Otherwise, the problem is false.

I didn't mean it that way!  I'm 21 and she's 20 LOL!

Modified/added:  I GET IT NOW!...White moves first, with a castling to prove he can castle...then the white rooks are lined up to check mate!
Title: Re: Mate in 2
Post by THUDandBLUNDER on Sep 22nd, 2003, 9:30pm
Yeah, Lightboxes, that's more-or-less it. Well done! Obviously, your son will be no quitter.  :D

:[hide]
Let W = White can still castle
Let B = Black can still castle.

In an earlier post you proved
(W and B) implies notB
You wrongly concluded notB, rather than not(W and B)

In other words, we cannot prove that White cannot still castle or that Black cannot still castle.
But we can prove that they cannot both still castle.

As we cannot prove that White cannot still castle, it is legal for him to do so.
But once White castles, Black cannot do so.

Conversely, if White does not castle (eg, plays 1. Rxa7), Black can still castle. [/hide]
Title: Re: Mate in 2
Post by Barukh on Sep 22nd, 2003, 11:40pm

on 09/22/03 at 06:56:24, THUDandBLUNDER wrote:
The first one belongs in Easy. I only posted it in this thread because it's a Mate in 2.

The second one could be described as Medium, but only just.

What about having a new forum "Chess"? Then, all this classification is settled once and forever. I have seen several brilliant chess puzzles in this forum (including the ones in this thread), and I'm sure there are many more around.
Title: Re: Mate in 2
Post by wowbagger on Sep 23rd, 2003, 6:58am
So we are actually playing on Schrödinger's board, aren't we? ;D

As long as we don't know for sure, both W and B are possible. This means our board is a linear superposition of a W-board and a B-board. Once White plays 0-0-0, our board collapses to an eigenstate, namely the one which was W (as White has just castled) - which prevents Black from castling. I have to wonder how you prepared the board in this peculiar state at the beginning.

On grounds of mental health, I vote against quantum chess problems...
Title: Re: Mate in 2
Post by wowbagger on Sep 23rd, 2003, 7:06am

on 09/22/03 at 23:40:14, Barukh wrote:
What about having a new forum "Chess"? Then, all this classification is settled once and forever.

There has already been such a suggestion, a discussion about other possible new sections takes place here (http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_general;action=display;num=1063677049).


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