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        riddles >> easy >> Mate in 1
        
(Message started by: THUDandBLUNDER on Sep 21^st, 2003, 8:20am)

Title: Mate in 1
Post by THUDandBLUNDER on Sep 21^st, 2003, 8:20am

Find the checkmate in 1 move!

Title: Re: Mate in 1
Post by Ulkesh on Sep 21^st, 2003, 10:21am

...
[hide]
Mate in 1 requires it to be black's turn. The two moves available to black are Rxa7 to which the correct reply is Rc8#, and Kxa7 to which the reply is b8=N#[/hide]

Title: Re: Mate in 1
Post by Sir Col on Sep 21^st, 2003, 3:37pm

What if [hide]black played Kxc7? I suppose white could play b8=R#. But whichever way, isn't that checkmate in 2 moves[/hide]?

Title: Re: Mate in 1
Post by Ulkesh on Sep 21^st, 2003, 4:31pm

on 09/21/03 at 15:37:17, Sir Col wrote:

What if [hide]black played Kxc7? I suppose white could play b8=R#. But whichever way, isn't that checkmate in 2 moves[/hide]?

[hide]Sorry, I missed that one. If black plays Kxc7, b7xa8=N# would do the job. It's still one only one move. One move in chess is actually composed of both white and black moving a piece.[/hide]

Title: Re: Mate in 1
Post by THUDandBLUNDER on Sep 22^nd, 2003, 9:37am

Checkmate in 1 move!

Title: Re: Mate in 1
Post by wowbagger on Sep 22^nd, 2003, 9:47am

1. [hide]Nxf7+[/hide]
or
1. [hide]... Nxc2+[/hide]

Title: Re: Mate in 1
Post by THUDandBLUNDER on Sep 22^nd, 2003, 9:56am

Nope.

Title: Re: Mate in 1
Post by wowbagger on Sep 22^nd, 2003, 10:02am

on 09/22/03 at 09:56:39, THUDandBLUNDER wrote:

Nope.

Why not? Seems perfectly valid to me. ???

Title: Re: Mate in 1
Post by BNC on Sep 22^nd, 2003, 10:31am

Err... is this a help-mate scenario?

Title: Re: Mate in 1
Post by THUDandBLUNDER on Sep 22^nd, 2003, 10:41am

Quote:

Err... is this a help-mate scenario?

No.

Quote:

Why not? Seems perfectly valid to me.

Do you think I would bother posting such an easy-peasy puzzle, especially one with two solutions? :P

Icarus could have come up with your answers, and in half the time! ;D

Title: Re: Mate in 1
Post by Ulkesh on Sep 22^nd, 2003, 10:54am

Wowbagger, I think...[hide] a little retrograde analysis would help. It limits the number of possibilities from what I can tell.[/hide]

Title: Re: Mate in 1
Post by Sir Col on Sep 22^nd, 2003, 12:49pm

wowbagger, reading between the lines (and I'm not usually much good at that) I think that T&B is saying, Nope, to your suggestion that both solutions are correct. I think he is being a little sneaky as I think that one of them is correct. However, the purpose is for us to determine which one it must be.

Having said that, could someone please explain these puzzles to me? ???

Where have the queens gone, and how did the opposing knights get behind line of pawns without being captured?

Title: Re: Mate in 1
Post by Ulkesh on Sep 22^nd, 2003, 1:06pm

Yes, Sir Col, I agree. I think the only mate allowed is the [hide]Black[/hide] one. Given the current position it's not possible for it to be [hide]White's[/hide] turn.

In answer to your other questions, it's irrelevant how badly either player may have played to lead to the current position (probably done co-operatively), the only important factor is what is possible/legal given the current position. In this case it can be shown simply enough which of wowbagger's initial answers is correct. I think T&B recently posted a puzzle where the method of solution was the same as for this puzzle.

Title: Re: Mate in 1
Post by BNC on Sep 22^nd, 2003, 1:45pm

I'd like to start by saying it's the first time I'm trying chess puzzles. The ones I used to see were "white starts and wins, what did he do?", the answer for which would be "Ka1b3". The knight in question would be way out of the "center of attraction", but the answer would go "black immediatlly sees he's doomed and quits". Well, thank-you-very-much!

These puzzles, I can understand (if not solve for now).

And now, my question: I understood from a previous puzzle that a chess move is actualy a move by both players. If that's the case, and it's :[hide]black's[/hide]: turn, he must ignore the possible mate, to allow the other side to complete his move and win. In my book, that's a help-mate, but T&B said "no" to that. Am I missing something?

Title: Re: Mate in 1
Post by Ulkesh on Sep 22^nd, 2003, 3:47pm

BNC, I think a bit of confusion may have arisen somewhere along the line here. When T&B says 'mate in 1 move', this literally means mate within one whole move. ie, if it is White's turn, he can mate straightaway without Black being able to respond, but rather than calling it a half move, standard chess definitions call this 'one move', despite it only being part of one whole move. Likewise, 'mate in two, white to play'-type puzzles, don't necessarily mean Black must deliver mate at the end of the second move, as long as mate is delivered (by either side) during the second move. This leads to a few more possibilities when solving chess puzzles.

Title: Re: Mate in 1
Post by Icarus on Sep 22^nd, 2003, 6:22pm

Despite T&B's taunts, I shall attempt to tackle this - with the help of an official set of rules:
[hide]
1) For every move, Knights switch the color square they are on. In this position, the black knights are on a square of each color, just as they are at the start. Therefore there have been an even number of black knight moves. Similarly, there have also been an even number of white knight moves.

2) All four rooks have been able at some point to move back and forth between their home squares and the adjacent ones, but no other moves have been possible. The fact that one rook on each side is out of home position indicates that both sides have made an odd number of rook moves.

3) The only other pieces that can possibly have moved are the Kings. White's king is in his starting position. Black's king is in his queen's position. Therefore white has made an even number of king moves, but black has made an odd number.

[therefore] White has moved an odd number of times. Black has moved an even number. Since white starts, it must be Black's move. And thus his move is the one that will mate.[/hide]

Title: Re: Mate in 1
Post by THUDandBLUNDER on Sep 22^nd, 2003, 7:41pm

A model answer, Icarus! :o

From now on I must find something else to stump you with. :(

Title: Re: Mate in 1
Post by Icarus on Sep 22^nd, 2003, 7:50pm

I doubt that will be a problem. Without Ulkesh's directions, I would still be scratching my head, and pretending the problem didn't actually exist!

Once I saw it as a symmetry problem however, it became familiar territory. :)

Title: Re: Mate in 1
Post by wowbagger on Sep 23^rd, 2003, 2:38am

on 09/22/03 at 10:41:57, THUDandBLUNDER wrote:

Do you think I would bother posting such an easy-peasy puzzle, especially one with two solutions? :P

Not really, but the solution I gave is not completely wrong. One obvious argument is that I wisely said "or", not "and" - so your "Nope" is at least misleading. :P
I have to postpone giving the other reason, because it's time for lunch now.

Quote:

Icarus could have come up with your answers, and in half the time! ;D

Come on, you don't even know how much time it actually took me! :)

Title: Re: Mate in 1
Post by THUDandBLUNDER on Sep 23^rd, 2003, 3:01am

Quote:

...wisely...

;D

Quote:

...but the solution I gave is not completely wrong.

That's right, it is merely wrong. :)

In my opinion, an answer of 'Correct move OR Illegal move' reveals no understanding of the puzzle and barely deserves a 'Nope'. :P

Title: Re: Mate in 1
Post by wowbagger on Sep 23^rd, 2003, 6:38am

on 09/23/03 at 03:01:42, THUDandBLUNDER wrote:

Watch your smilies!

Quote:

That's right, it is merely wrong. :)

No it's not!

Quote:

In my opinion, an answer of 'Correct move OR Illegal move' reveals no understanding of the puzzle and barely deserves a 'Nope'. :P

You could have just ignored it... But in that case you'd have one post less right? ;)

on 09/22/03 at 10:54:41, Ulkesh wrote:

Wowbagger, I think...[hide] a little retrograde analysis would help.[/hide]

As has become clear by now, this is what T&B intended. This was not asked for, however.

Let me make this very clear once and for all: I'm not a regular chess problem solver, I'm a regular chess player - which is a huge difference as most of those who read this may know. It has always been my view (because nobody told me the contrary) that starting positions in chess problems should be sensible, by which I mean that not both kings can be in check, for example. But even positions with one side having eleven knights shouldn't be ruled out a priori. After all, it's a composed problem, thus the position is often one that is usually not encountered in actual play and may even be inaccessible by legal moves.
As long as there is no indication that the solution should involve some retrograde analysis, I see these as ordinary chess problems. This is the main reason why I am satisfied with my solution(s): "Checkmate in 1 move" was sought, and I found two! I knew that these were not what T&B was really looking for, but my answer fits the question.
(I could relate a story about an exam question involving an ideal gas inside a cube, but moving only along the x-axis. The question was to calculate the pressure on one side of the cube...)

on 09/22/03 at 15:47:32, Ulkesh wrote:

When T&B says 'mate in 1 move', this literally means mate within one whole move. ie, if it is White's turn, he can mate straightaway without Black being able to respond, but rather than calling it a half move, standard chess definitions call this 'one move', despite it only being part of one whole move.

According to the definition (http://www.chessvariants.com/fidelaws.html), a move is actually "the transfer by a player of one of his pieces from one square to another square, which is either vacant or occupied by an opponent's piece", with the exception of castling. (I know this is in conflict with the common use of language, as when we say that a game took 42 moves.)
The interpretation of "mate in two" is then "checkmate within at most two moves by the mating side", I'd say.

Title: Re: Mate in 1
Post by Lightboxes' Clone on Sep 23^rd, 2003, 3:18pm

check out these links for variations of chess:
http://www-stu.christs.cam.ac.uk/~amj26/random/chess.html
http://www.tursiops.cc/idhop/recroom/chessvar.htm
http://www.abstractstrategy.com/chess-g.html

And of course other variations that don't require any special products:
****Instead of capturing a piece and taking it off the board, you have to keep it on the board but you can place it anywhere.
****Put a barrier down the middle of the board so neither of you can see the other side. Setup your side whichever way you choose and the opponent too. Remove the barrier and play.
****The first person that goes (you) moves 1 move, your opponent moves 2 moves, then you move 3, etc...

Title: Re: Mate in 1
Post by Icarus on Sep 23^rd, 2003, 5:47pm

on 09/23/03 at 06:38:00, wowbagger wrote:

After all, it's a composed problem, thus the position is often one that is usually not encountered in actual play and may even be inaccessible by legal moves.
As long as there is no indication that the solution should involve some retrograde analysis, I see these as ordinary chess problems.

I think Wowbagger's got you dead to rights here, T&B. I seem to recall you saying elsewhere (too lazy to go look), that the sensibility or even legality of the initial position is not required in a chess puzzle. By that standard, and without any additional instruction in the original problem, both of Wowbagger's solutions are correct.

Title: Re: Mate in 1
Post by THUDandBLUNDER on Sep 24^th, 2003, 4:25am

on 09/23/03 at 17:47:22, Icarus wrote:

I seem to recall you saying elsewhere (too lazy to go look), that the sensibility or even legality of the initial position is not required in a chess puzzle. By that standard, and without any additional instruction in the original problem, both of Wowbagger's solutions are correct.

I was referring to standard mate puzzles.
This was a retro puzzle, as were all the other chess puzzles I have posted.

I also wrote in another thread:
"I don't think it's worth posting boring run-of-the-mill mate-in-x-moves puzzles in this forum."
I certainly don't see any point in posting a standard mate-in-ONE-move puzzle.

Quote:

You could have just ignored it... But in that case you'd have one post less right?

Wrong. Happily, I do not share some people's unhealthy fascination with post count. ;)

Title: Re: Mate in 1
Post by wowbagger on Sep 24^th, 2003, 5:20am

on 09/24/03 at 04:25:05, THUDandBLUNDER wrote:

I was referring to standard mate puzzles.
This was a retro puzzle, as were all the other chess puzzles I have posted.

That's exactly the point. It is not obvious that it's a retro puzzle. Maybe forum (and chess riddle) regulars know you well enough by now, but a guest might be really puzzled. ;)
You could have added something like "Find the unique checkmate within one move", although even that is probably not clear enough. I suggest to indicate it when retrograde analysis is expected, even though this may be considered a hint. It will surely help those who have never encountered such problems before.

Quote:

Happily, I do not share some people's unhealthy fascination with post count. ;)

I don't know who you mean - I'm feeling quite healthy... *coughs discreetly*

Title: Re: Mate in 1
Post by Ulkesh on Sep 24^th, 2003, 8:47am

I actually kind of agree with T&B on this issue. I believe the way the puzzle was originally posed is the best way. Perhaps the 'Nope' may have been misleading, but that's beside my point.

I've seen a number of (usually easy) puzzles on the forums where to people well-versed at lateral thinking and general puzzle-solving techniques, the answer is obvious. A lot of these people then turn into pedants and pick holes in the wording of the original puzzle and try to come up with as many creative answers as possible, so long as they fit the literal meaning (as opposed to intended meaning) of the puzzle. I do not regard this as a bad thing at all -- I feel that it's a good show of puzzle solving skill to think laterally like this (as do many interviewers by the look of the MS forum).

There is a direct analogy between those puzzles and this chess puzzle. I see nothing wrong with looking at all aspects of the puzzle to find better or different answers. One good answer may be the two solutions Wowbagger gave. But upon further thought (using the initial setup of this puzzle as an analogy to the wording of the easy puzzles), retrograde analysis might help, and a better solution may be obtained. More thought leads to the puzzler digging deeper into the heart of the puzzle (analogous to disecting the meaning of the easy puzzles), to find different, and perhaps better answers. By better, I mean more intuitively appealing. The main difference between the easy puzzles I mentioned and this one is that the intended answer for the easy puzzles is the simple one and the intended answer for this is the pedantic one. But since many of the puzzlers here are so good at analysing the wording of easy puzzles, why not analyse the inital position of this one in greater detail?

I also don't believe ignorance of how to solve chess problems is an excuse. Some people may be useless at solving the types of riddles found on this website, but they learn. Chess may be a very specific and specialised form of puzzle solving, but it doesn't take much effort to learn the standard conventions.

People may argue that standard 'mate in X' puzzles found in newspapers don't expect you to use retrograde analysis to determine the legality of a particular player's move, and don't say that you shouldn't. This puzzle doesn't say that you should. Which is correct? Well, there's no easy answer to this apart from using your judgement. It's usually obvious that there is more to an easy-looking puzzle than meets the eye (as I believe there is in this puzzle). As with puzzles, a good chess player will see a 'trick' in a setup/question more quickly than a bad one.

Title: Re: Mate in 1
Post by wowbagger on Sep 25^th, 2003, 4:49am

on 09/24/03 at 08:47:59, Ulkesh wrote:

But upon further thought (using the initial setup of this puzzle as an analogy to the wording of the easy puzzles), retrograde analysis might help, and a better solution may be obtained. More thought leads to the puzzler digging deeper into the heart of the puzzle (analogous to disecting the meaning of the easy puzzles), to find different, and perhaps better answers. By better, I mean more intuitively appealing. The main difference between the easy puzzles I mentioned and this one is that the intended answer for the easy puzzles is the simple one and the intended answer for this is the pedantic one. But since many of the puzzlers here are so good at analysing the wording of easy puzzles, why not analyse the inital position of this one in greater detail?

I didn't say that one shouldn't analyse the initial position, nor that the answer based upon such an analysis is wrong. My main point was that a retrograde analysis wasn't asked for, but my answer wasn't accepted as correct.

Regarding your analogy: The lateral thinking and/or pedantic interpretation of those easy puzzles generally leads to new, different answers that can be justified by the specific interpretation used. Here, however, one could say that the retrograde analysis doesn't give a new answer. Rather, it excludes one of the previously "correct" and thus makes the solution unique - which is nice, but wasn't asked for. Apart from the uniqueness, I don't think the single answer arrived at by retrograde analysis is more intuitive than the other one. Especially as it's founded on an important, but not readily obvious, assumption: that the initial setup is the result of an actual game of chess.

Quote:

I also don't believe ignorance of how to solve chess problems is an excuse.

I didn't post that in order to give an excuse, but to try to make my situation clear.

Quote:

Some people may be useless at solving the types of riddles found on this website, but they learn. Chess may be a very specific and specialised form of puzzle solving, but it doesn't take much effort to learn the standard conventions.

Hopefully I'm among those who learn... :-/
Would you say, then, that the standard conventions of chess problems require the initial setup to be one that can be reached by a legal game of chess?

Quote:

People may argue that standard 'mate in X' puzzles found in newspapers don't expect you to use retrograde analysis to determine the legality of a particular player's move, and don't say that you shouldn't. This puzzle doesn't say that you should. Which is correct? Well, there's no easy answer to this apart from using your judgement. It's usually obvious that there is more to an easy-looking puzzle than meets the eye (as I believe there is in this puzzle).

Yes, it is - I thought so and already said so. Maybe I was just being more pedantic than intended, so I didn't arrive at the intended pedantic answer. ;)

Quote:

As with puzzles, a good chess player will see a 'trick' in a setup/question more quickly than a bad one.

In a "common" setup (resembling positions that actually occur in games), he certainly will. This doesn't necessarily carry over to solving chess problems, however. As is well known (I think), problems are often quite far from any "chess reality". That's why there are people versed in solving chess problems who aren't as good in playing, just as there are those for who it's the other way round.

Title: Re: Mate in 1
Post by Ulkesh on Sep 25^th, 2003, 1:19pm

Quote:

I'd agree that your answer isn't incorrect per se given the way the puzzle was originally posed. However, I'd say that Icarus' later answer is a better answer, as more things have been taken into account.

Quote:

Regarding your analogy: The lateral thinking and/or pedantic interpretation of those easy puzzles generally leads to new, different answers that can be justified by the specific interpretation used. Here, however, one could say that the retrograde analysis doesn't give a new answer. Rather, it excludes one of the previously "correct" and thus makes the solution unique - which is nice, but wasn't asked for.

Apart from the uniqueness, I don't think the single answer arrived at by retrograde analysis is more intuitive than the other one. Especially as it's founded on an important, but not readily obvious, assumption: that the initial setup is the result of an actual game of chess.

Fair point; the assumption isn't obvious, but it's very nearly that in my opinion. Many easier standard puzzles don't make it totally obvious at first what is needed, but it is easy to infer what is. This puzzle requires you to make the inferrence, which I'd say is perfectly fair. I'd also agree that the answer is not totally intuitive, but once it is known, it is certainly more appealing.

Quote:

I didn't post that in order to give an excuse, but to try to make my situation clear.

I wasn't taking a swipe at you specifically! I was talking generally. No offence intended. :)

Quote:

Would you say, then, that the standard conventions of chess problems require the initial setup to be one that can be reached by a legal game of chess?

To be honest, I'm not sure. However, the vast majority of the time it is not necessary to make this distinction. When it is necessary, as is the case here, I believe the assumption that the game developed from the usual starting positions can be expected without prompting, as it is a logically simple and readily apparent one to make. Consider it part of the puzzle, if you like: to reveal the more appealing answer, a simple assumption must be made. However, I disagree that any of this need be stated along with the puzzle. It's part of the hardship of being an uberpuzzler (I should be so lucky!) that some degree of an ability to 'think outside the box' can be assumed.

Quote:

Perhaps I should have said 'chess problem solver' as opposed to 'chess player'. I'd still say there is a strong correlation between the two skills though, despite the odd exception.

Title: Re: Mate in 1
Post by Icarus on Sep 25^th, 2003, 3:31pm

Wowbagger's complaint is that - although nothing in the original question gives any indication that retrograde analysis is required, his answer was declared incorrect for not having included it. Since puzzles of this sort are given without the requirement of retrograde analysis to see which answers are in legal games, it was unfair to say that his answer was error. T&B would have done better to indicate that more analysis was needed, rather than simply to declare the answer wrong.

Title: Re: Mate in 1
Post by Ulkesh on Sep 25^th, 2003, 5:03pm

I agree with that, Icarus, and have done from the start (see the beginning of my reply #25). The discussion has branched off into many directions though, and I think my main point is now that T&B was justified in not explicitly saying that retrograde analysis, and the assumption that the position came from a real game of chess were required to reach the intended solution. Broadly speaking, I believe figuring this out is all part of the puzzle solving process.

Title: Re: Mate in 1
Post by wowbagger on Sep 26^th, 2003, 4:34am

on 09/25/03 at 13:19:17, Ulkesh wrote:

However, I'd say that Icarus' later answer is a better answer, as more things have been taken into account.

That's okay with me. I wouldn't want to take credit from Icarus in these rare circumstances. Now that he has solved a chess puzzle, we have to find something else to challenge him. ;)

Quote:

And why should it be asked for? People aren't prompted to think laterally when a problem isn't worded so that it excludes every possibility bar the intended one, but they do anyway. Why should a given retrograde chess puzzle be different?
I think the only reasonable answer to this question would be: Because the retrograde thinking is intended. However, this doesn't really require an explicit indication, I guess. Not for those who are familiar with retrograde analysis, at least. When I suggested a more specific question, it was with other puzzlers in mind.
It's definitely more satisfying if one comes up with the crucial idea oneself and arrives at Icarus's conclusion than if a clue was given.

Many easier standard puzzles don't make it totally obvious at first what is needed, but it is easy to infer what is. This puzzle requires you to make the inferrence, which I'd say is perfectly fair. I'd also agree that the answer is not totally intuitive, but once it is known, it is certainly more appealing.

Agreed.

Quote:

No offence intended. :)

I thought so. :)

Quote:

Well, I'll try to remember this discussion when the next possibly retro puzzle comes up. Which doesn't mean I won't post any trivial but (imho) correct answers! :D

on 09/25/03 at 15:31:46, Icarus wrote:

Wowbagger's complaint is that - although nothing in the original question gives any indication that retrograde analysis is required, his answer was declared incorrect for not having included it.

Yes, that's the original point at issue.

on 09/25/03 at 17:03:56, Ulkesh wrote:

The discussion has branched off into many directions though,

Which is not a bad thing altogether...

Quote:

and I think my main point is now that T&B was justified in not explicitly saying that retrograde analysis, and the assumption that the position came from a real game of chess were required to reach the intended solution. Broadly speaking, I believe figuring this out is all part of the puzzle solving process.

I think that's right. It's T&B's nopey-dopey response that set me off. ;)