Chess Logic Question
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Assume that you have a situation where the King is in check from more than one piece. Is it possible to have such a situation where you can move one piece, other than the King, and get out of check? If so, explain your answer please.
Everything makes sense in someone's mind
There are three ways to get out of a simple check: capturing the checking piece, putting something in between the checking piece and the king (not if there are no empty squares in between, and also not if the attacker is a knight), and moving the king. There is basically one way to give a double check, it is always a "discovered check", and essentially the two checking actions are by different pieces and work in different directions; different pieces means you can't capture both, different directions means you can't put something in between to block both checks. On a double check, the only escape is by moving the king. Here are some examples of discovered check (using algebraic notation): (1) White Kh1, Re5, Bd4; Black Kh8. Discovered single checks would be most rook moves; double checks would be Re8 or Rh5. (2) White Kh1, Ne5, Bd4; Black Kh8. Discovered single checks would be most knight moves; double checks would be Nf7 or Ng6. (3) White Kh1, Re1, pe2; Black Ke4, pd3. The only check is a double one: pawn e2 takes d3. You can easily verify none of those can be recovered from without moving the black king. It is impossible to offer a triple check; moving a piece can cause a check by that piece itself, and by the one piece it discovers, as in the examples above. :)
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yes. en passant.
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Nope. See my other reply. :)
Luc Pattyn [Forum Guidelines] [My Articles] Nil Volentibus Arduum
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Assume that you have a situation where the King is in check from more than one piece. Is it possible to have such a situation where you can move one piece, other than the King, and get out of check? If so, explain your answer please.
Everything makes sense in someone's mind
... no substitute for a good blaster at your side. :cool:
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Assume that you have a situation where the King is in check from more than one piece. Is it possible to have such a situation where you can move one piece, other than the King, and get out of check? If so, explain your answer please.
Everything makes sense in someone's mind
Kevin Marois wrote:
other than the King, and get out of check?
No. Not that I'm aware of.
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Assume that you have a situation where the King is in check from more than one piece. Is it possible to have such a situation where you can move one piece, other than the King, and get out of check? If so, explain your answer please.
Everything makes sense in someone's mind
Not enough detail. If would depend on the pieces putting the king in check and their positions on the board. Bishops, Knights, Queen, Castles, pawns or some combination. Castling can sometimes handle the problem but that is not one piece and does involve the king.
"Coding for fun and profit ... mostly fun"
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Getting put into check by 2 or even 3 pieces can easily happen. The question is, can you get out of a double check with only one move (other than moving the King)?
Everything makes sense in someone's mind
Yes, of course... it is called a full combo... I used it a lot in the street fighter games...
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Not enough detail. If would depend on the pieces putting the king in check and their positions on the board. Bishops, Knights, Queen, Castles, pawns or some combination. Castling can sometimes handle the problem but that is not one piece and does involve the king.
"Coding for fun and profit ... mostly fun"
You are not allowed to castle while in check anyway.
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Assume that you have a situation where the King is in check from more than one piece. Is it possible to have such a situation where you can move one piece, other than the King, and get out of check? If so, explain your answer please.
Everything makes sense in someone's mind
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Assume that you have a situation where the King is in check from more than one piece. Is it possible to have such a situation where you can move one piece, other than the King, and get out of check? If so, explain your answer please.
Everything makes sense in someone's mind
Sure it is... Assume that two white pieces, such as, a rook & queen, check along the same file. If the black can move off the file or interpose, no double check. Note: Some define "double check" as a condition which forces the king to move. For those, the question is moot. ;-)
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Not enough detail. If would depend on the pieces putting the king in check and their positions on the board. Bishops, Knights, Queen, Castles, pawns or some combination. Castling can sometimes handle the problem but that is not one piece and does involve the king.
"Coding for fun and profit ... mostly fun"
dpminusa wrote:
Not enough detail. If would depend on the pieces putting the king in check and their positions on the board. Bishops, Knights, Queen, Castles, pawns or some combination. Castling can sometimes handle the problem but that is not one piece and does involve the king.
Detail doesn't matter. If it's not possible, it's not possible. It was nice of you to list chess pieces though :-) (they're called "rooks", not "castles"). And castling can't "sometimes" handle the problem, it never can. Not only would the king move making it invalid for this problem, but a standard rule of chess is that you can't castle out of check ever. The only way it would be possible would be if there were a discovered check where 2 rooks were on the same rank or file as the king, or a bishop and queen (or 2 bishops) on the same diagonal as the king. However that would be really stretching it because under normal terminology the king is not under check by both those pieces - only 1 of them. Of course if 1 of the pieces involved in the discovered check is a knight, then nothing can be done because a knight's path can never be blocked. Only 1 of the 2 pieces can be blocked, and only 1 of the 2 pieces can be captured. For those of you about to jump on my "2 bishops on same diagonal" comment, technically that is possible if you promoted a pawn to a bishop for some reason. (Normally the only reason to avoid promoting to a queen is if stalemating the opposing king by the promotion is a concern, either immediately or if you're worried about making a mistake down the road in a speed chess match.)
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Sure it is... Assume that two white pieces, such as, a rook & queen, check along the same file. If the black can move off the file or interpose, no double check. Note: Some define "double check" as a condition which forces the king to move. For those, the question is moot. ;-)
tf_ics wrote:
Sure it is... Assume that two white pieces, such as, a rook & queen, check along the same file. If the black can move off the file or interpose, no double check.
As I wrote in my other post, that is not considered "double check" by standard terminology. Only 1 piece has put the king in check. Double check is not "defined" as a condition which forces the king to move, but simply that double check is 2 checks from 2 pieces in 2 different directions, and it so happens that the only way out of this is to move the king. I assume there's a typo in your post, where you said "if the black can move off the file or interpose." If that was supposed to be "if the black king can move off the file or another piece can interpose", then there's a third way out of the situation you described. For example if you have 2 connected rooks and one of them gives discovered check, then by capturing that rook you are simultaneously blocking the other rook from giving check. This sounds like a homework problem or something, and I wonder if the teacher might be expecting an answer when he doesn't fully understand the problem or rules.
modified on Wednesday, December 29, 2010 1:57 PM
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Assume that you have a situation where the King is in check from more than one piece. Is it possible to have such a situation where you can move one piece, other than the King, and get out of check? If so, explain your answer please.
Everything makes sense in someone's mind
If you are in double-check, then it is via a discovered check in which your opponent puts you in check from both the piece that he moves and another piece that is unblocked by the move. If there is a way out other than moving your king, then it requires capturing one of the checking pieces and blocking the other checking piece in the same move. If you capture one checking piece and block another checking piece in the same move, then you are capturing a piece in one space while moving to a different space. If you are capturing a piece in one space while moving to a different space, then it is en passant. If you capture en passant, then your opponent's previous move was advancing a pawn two spaces from its initial position. If your opponent introduced a double-check by moving a pawn, then that pawn must be one of the pieces that is attacking your king. If an opposing pawn is attacking your king, then your king must be in one of two positions. There is no way that your opponent could introduce a discovered check upon either of your king's possible positions from any other position that was previously blocked by the pawn that he moved. Therefore, if you are in double-check, then it is impossible to get out of check by moving any piece other than your king.
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If you are in double-check, then it is via a discovered check in which your opponent puts you in check from both the piece that he moves and another piece that is unblocked by the move. If there is a way out other than moving your king, then it requires capturing one of the checking pieces and blocking the other checking piece in the same move. If you capture one checking piece and block another checking piece in the same move, then you are capturing a piece in one space while moving to a different space. If you are capturing a piece in one space while moving to a different space, then it is en passant. If you capture en passant, then your opponent's previous move was advancing a pawn two spaces from its initial position. If your opponent introduced a double-check by moving a pawn, then that pawn must be one of the pieces that is attacking your king. If an opposing pawn is attacking your king, then your king must be in one of two positions. There is no way that your opponent could introduce a discovered check upon either of your king's possible positions from any other position that was previously blocked by the pawn that he moved. Therefore, if you are in double-check, then it is impossible to get out of check by moving any piece other than your king.
JLengi wrote:
If you are capturing a piece in one space while moving to a different space, then it is en passant. If you capture en passant, then your opponent's previous move was advancing a pawn two spaces from its initial position. If your opponent introduced a double-check by moving a pawn, then that pawn must be one of the pieces that is attacking your king.
Not quite sure what you're implying here, but it is possible to capture a pawn en passant, which delivers a double discovered check, without your capturing pawn giving check. Wikipedia shows an example of this http://en.wikipedia.org/wiki/Double_check[^]
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JLengi wrote:
If you are capturing a piece in one space while moving to a different space, then it is en passant. If you capture en passant, then your opponent's previous move was advancing a pawn two spaces from its initial position. If your opponent introduced a double-check by moving a pawn, then that pawn must be one of the pieces that is attacking your king.
Not quite sure what you're implying here, but it is possible to capture a pawn en passant, which delivers a double discovered check, without your capturing pawn giving check. Wikipedia shows an example of this http://en.wikipedia.org/wiki/Double_check[^]
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It is possible to deliver a double-check en passant. But it is not possible to get out of double-check en passant. If your opponent's last move was en passant, then it is impossible for your next move to be en passant.
JLengi wrote:
It is possible to deliver a double-check en passant. But it is not possible to get out of double-check en passant.
I was saying it's possible to deliver a double check en passant even without the pawn giving check. But with regard to your second point, I'd have to agree that's true.
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dpminusa wrote:
Not enough detail. If would depend on the pieces putting the king in check and their positions on the board. Bishops, Knights, Queen, Castles, pawns or some combination. Castling can sometimes handle the problem but that is not one piece and does involve the king.
Detail doesn't matter. If it's not possible, it's not possible. It was nice of you to list chess pieces though :-) (they're called "rooks", not "castles"). And castling can't "sometimes" handle the problem, it never can. Not only would the king move making it invalid for this problem, but a standard rule of chess is that you can't castle out of check ever. The only way it would be possible would be if there were a discovered check where 2 rooks were on the same rank or file as the king, or a bishop and queen (or 2 bishops) on the same diagonal as the king. However that would be really stretching it because under normal terminology the king is not under check by both those pieces - only 1 of them. Of course if 1 of the pieces involved in the discovered check is a knight, then nothing can be done because a knight's path can never be blocked. Only 1 of the 2 pieces can be blocked, and only 1 of the 2 pieces can be captured. For those of you about to jump on my "2 bishops on same diagonal" comment, technically that is possible if you promoted a pawn to a bishop for some reason. (Normally the only reason to avoid promoting to a queen is if stalemating the opposing king by the promotion is a concern, either immediately or if you're worried about making a mistake down the road in a speed chess match.)
I am not sure what your anger is about. It does not seem to be appropriate on a forum that hopes to build interest and membership. At one point I played competitive chess. A slang term for rooks is castles (many people I knew called the rooks castles). You are right that you cannot castle out of check. I did not read the question that check was present but that check was eminent. Lighten up, dude.
"Coding for fun and profit ... mostly fun"
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I am not sure what your anger is about. It does not seem to be appropriate on a forum that hopes to build interest and membership. At one point I played competitive chess. A slang term for rooks is castles (many people I knew called the rooks castles). You are right that you cannot castle out of check. I did not read the question that check was present but that check was eminent. Lighten up, dude.
"Coding for fun and profit ... mostly fun"
dpminusa wrote:
I am not sure what your anger is about.
I'm not sure why you picked up on anger. I simply replied to the inaccuracies in your post. You might have played "competitive" chess, whatever you mean by that, but it doesn't make your post any more authoritative. The original question was relatively logical and technical in nature - effectively a math problem - and I think you'll find on any technical forum if you post an incorrect answer you're going to get corrected. At least I hope so - that's really one of the main reasons for having a public forum - so answers can get peer reviewed and corrected, making the whole process much more valuable. I'm sure if you asked a question here and got conflicting answers, you'd appreciate somebody clearing up the discrepancies. So.... lighten up dude :)
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dpminusa wrote:
I am not sure what your anger is about.
I'm not sure why you picked up on anger. I simply replied to the inaccuracies in your post. You might have played "competitive" chess, whatever you mean by that, but it doesn't make your post any more authoritative. The original question was relatively logical and technical in nature - effectively a math problem - and I think you'll find on any technical forum if you post an incorrect answer you're going to get corrected. At least I hope so - that's really one of the main reasons for having a public forum - so answers can get peer reviewed and corrected, making the whole process much more valuable. I'm sure if you asked a question here and got conflicting answers, you'd appreciate somebody clearing up the discrepancies. So.... lighten up dude :)
As feedback, I don't agree with your comment that "the details don't matter". My comment about playing competitive chess for 5 years was to indicate that I do know the rules of chess. If I misread your tone then OK. It seemed a bit snooty. How does snooty help anyone? Critique and clarification is great. You are right that that this is part of any technical forum. I participate in dozens of them on dozens of topics each week. I am sure most of the people posting here do the same thing. Many of them have a courteous tone that encourages participation. I have several degrees, one is in math. I know it is a math problem. I felt, and still do, that it could be a bit more clearly defined to facilitate a solution. I believe that defining a problem is critical to solving it. Perhaps like coding without a clear spec. It is an interesting problem. Clearly the questioner is very sharp. This forum has interesting topics much of the time. Lets stay constructive and consider all points of view and approaches to problem solving. Not everyone solves a problem the same way. If they did we would not have 80% of the calculus we have now. Thanks for your feedback.
"Coding for fun and profit ... mostly fun"
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As feedback, I don't agree with your comment that "the details don't matter". My comment about playing competitive chess for 5 years was to indicate that I do know the rules of chess. If I misread your tone then OK. It seemed a bit snooty. How does snooty help anyone? Critique and clarification is great. You are right that that this is part of any technical forum. I participate in dozens of them on dozens of topics each week. I am sure most of the people posting here do the same thing. Many of them have a courteous tone that encourages participation. I have several degrees, one is in math. I know it is a math problem. I felt, and still do, that it could be a bit more clearly defined to facilitate a solution. I believe that defining a problem is critical to solving it. Perhaps like coding without a clear spec. It is an interesting problem. Clearly the questioner is very sharp. This forum has interesting topics much of the time. Lets stay constructive and consider all points of view and approaches to problem solving. Not everyone solves a problem the same way. If they did we would not have 80% of the calculus we have now. Thanks for your feedback.
"Coding for fun and profit ... mostly fun"
dpminusa wrote:
As feedback, I don't agree with your comment that "the details don't matter".
Sorry if I sounded snooty. However, you responded to the original question with "not enough detail". That's simply not true. The OP asked what was a pretty cut and dried question that didn't need any more detail to answer. It would be as if he asked "is it possible to assign integer values for X and Y such that X + Y = SquareRoot(3)", and you answered "not enough detail - it depends on the values of X and Y." That's simply incorrect. It's not personal, I was just simply correcting your answer for the benefit of the OP. The answer to his question is "no", and the answer doesn't depend on the combination of pieces putting the king in check, as you stated. Nor can castling "sometimes handle the problem". Again, it's not personal, it's simply factually incorrect. (OK I had some fun with "castles", but hey let's be honest - the only people who use that term are 4 year olds and non-chess-players.) But since you brought it up, you have described yourself as a "competitive" chess player, and someone with "several degrees", including math. I haven't posted my credentials, so one might ask you the same question you asked me - how does being snooty help anyone? Credentials don't matter much when the answer is wrong. I agree the problem was interesting. Is defining a problem critical to solving it? Obviously. Was there any more information we needed to know to answer his question? No, it was very straightforward, concise, well-defined and complete as written. I'm genuinely curious about what you thought was missing that was necessary to formulate a correct answer. In fact the question was so concise and well-defined that I'm also curious as to why you think the OP is "clearly very sharp". I suspect he merely copied that question from someone else, which is fine (although if it was a homework assignment that probably should have been stated), but it doesn't make him "clearly very sharp". Maybe he is, but actually I think many people could have gotten an answer by some clever Googling in about the time it took him to post the question.