Answers.Body: <p>I would let the checkmate stand but the true answer is that it does not matter. The player has the right to offer a draw at any time and the claim according to article 9.3 is also a draw offer. You are concerned with a peculiar situation where player A wants a draw and does not want to win, for whatever reason, while player B does not want to draw (even at the cost of a loss). Therefore, the question you really ask is whether claiming a draw according to article 9.3, if the intended move delivers a checkmate, can secure you the draw. Abstracting away from the possibility that you can choose any other legal move and claim on that basis, the answer to that question is that yes, there is a way. </p>
  
  <p>You can claim the draw as you proposed and if the arbiter rejects the claim because the checkmate stands then you simply let your time run out and the game is a draw because the opponent cannot checkmate you by any series of legal moves. This is since you have committed to play the checkmating move thus there is no way how the opponent could checkmate you as they are going to be checkmated on next move. A catch is that not all arbiters may be comfortable with this interpretation and they may declare the game lost for you even though they shouldn't. But this situation will never happen anyway, right? It is purely of academic interest. </p>
  
  <p>I would let the checkmate stand for two reasons.</p>
  
  <ol>
  <li>Consider this variation on your question, you claim the draw as you proposed but the intended move does not deliver a checkmate but rather captures a pawn. Again, as you point out, the move has not yet been made, hence, the pawn is never captured. Still the claim should be rejected. To assess the validity of the claim you need to consider the position as if the move had been played. I would apply this reasoning to the checkmate situation. If there is a checkmate after the intended 50th move, the validity of the claim cannot be assessed since the game will have finished. Of course, you can choose another move and claim the draw. </li>
  <li>Article 9.6.2 explicitly says that the checkmate takes precedence, therefore, I would apply it to article 9.3.1 too (not 9.3.2 since the game would have already finished once the checkmate is on the board). The crux is whether article 9.3.1 omits to mention this precedence intentionally. If this was so then what would the intention be? The intention would have to be to allow the player to secure a draw instead of the win and this is pointless as I explained earlier. Therefore, this difference in the wordings is not intentional, in fact, article 9.3.1 does not require it while article 9.6.2 does. In the situation described in 9.6.2 the player does not have the option not to claim, the amendment protects the stronger player here. </li>
  </ol>
  
  <p>It does not really matter though. Imagine 50 moves without a capture or moving a pawn have already been played. Then the player can either claim according to 9.3.1 as you proposed or they can claim according to 9.3.2 even though they could deliver a checkmate next move. In the latter case it is an unambiguous draw. It does not make much sense to obtain to different results depending on which way you claim the same thing (yes, I am undermining my earlier arguments) but either way you get something out of it that does not make much sense. But again, no one forces you to claim a draw with a checkmating move. In fact, this may trigger a punishment according to article 12.9 for putting chess in disrepute. </p>
  
  <p>I am afraid you misunderstand Geurt Gijssen's answer. He did not answer your question at all, he said that the player having the move would not make the claim, because it does not make sense, and the opponent is not allowed to make the claim, because it is not their move. It does not follow from his answer that he would agree with the claim if the player really made it.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T13:35:59.687Z
Answers.Text: Your whole answer is interesting to me (even though I have voted to close my own question). I especially like your point regarding article 12.9. If you want to know, I was thinking of someone like the programmer of an online interface for chess play. They're writing a program, and the program cannot know anything about article 12.9, yet regarding article 9.3, the program's logic cannot but be coded the one way or the other.
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T14:22:25.353Z
Answers.Text: Your IA title lends weight to your answer. Let me *accept* your answer for this reason.
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T15:17:32.520Z
Answers.Text: Who *downvoted* this answer? One can disagree with the answer's conclusion, but one can hardly characterize the answer as unreasonable or ill informed. That was an odd downvote.
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T12:01:05.710Z
Answers.LastActivityDate: 2018-01-23T12:01:05.710Z
Answers.UserDisplayName: IA Petr Harasimovic
Answers.Body: <p>The Laws of Chess say:</p>
  
  <blockquote>
    <p>9.3 The game is drawn, upon a correct claim by the player having the move, if</p>
    
    <p>a) he  writes his  move on  his  scoresheet  and  declares  to  the 
    arbiter  his  intention to make this move, which shall result in the
    last 50 moves having been made by each player without the movement of
    any pawn and without any capture, or</p>
    
    <p>b) the last 50 consecutive  moves  have  been  made  by  each  player
    without the movement of any pawn and without any capture.</p>
  </blockquote>
  
  <p>So you don't claim the draw WHILE you checkmate but BEFORE you make the checkmate move. Therefore there is no checkmate, but the game is drawn.</p>
  
  <p>If you don't claim the draw but execute your checkmate move, your opponent cannot claim a draw by 9.3.b) because the game is finished by your checkmate.</p>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T13:31:52.167Z
Answers.Text: I like the answer. Still, from experience with other games, I observe that stretching the mere accidental *wording* of a rule to cover situations the rule's writer did not consider is a practice that has never, as far as I know, produced agreement among players as to what the rule actually means. If players do not agree to meaning, then, in a sense, you don't even have a rule. I do not assert that you have stretched anything, of course, but see: another player has in good faith given an opposite answer in this very thread. So, maybe the FIDE could word the rule better?
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T18:05:03.750Z
Answers.Text: The rules are very clear. Rule 9.4 states: 
  "If the player touches a piece as in Article 4.3, he loses the right to claim a draw under Article 9.2 or 9.3 on that move." So you cannot claim a draw after or "during" the checkmate move. Either you claim a draw before touching a piece or you make the checkmate move and win.
Answers.UserDisplayName: muclux
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-24T19:17:52.083Z
Answers.Text: I have noticed that, in discussion of game rules, "clear" means "clear" but "very clear" invariably means "not clear at all," unfortunately. One must allow adequate scope for that reasonable, informed readers can read the same words and yet (to the mutual surprise of each) perceive opposite semantics therein. When reasonable, informed readers (including you and others in this thread) do perceive opposite semantics, does this not reveal a flaw in the words?
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T08:13:00.463Z
Answers.LastActivityDate: 2018-01-23T08:13:00.463Z
Answers.UserDisplayName: muclux
Answers.Body: <p>It appears that 1.4.2 and 5.1.1 on that page would take precedence.</p>
  
  <blockquote>
    <p>1.4.2 The opponent whose king has been checkmated has lost the game.   </p>
    
    <p>5.1.1 The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the move producing
    the checkmate position was in accordance with Article 3 and Articles
    4.2 – 4.7.</p>
  </blockquote>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T06:22:27.073Z
Answers.Text: Except that the checkmating move has not yet been made? I would not be asking except for the difference in wording between 9.3.1 and 9.6.2 in the new laws.
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T06:33:34.733Z
Answers.Text: I have never thought that rules should be read so literally that one extracts a meaning opposite to that which the rules' writer intended. However, in this case, you have 9.3.1, and you have 9.6.2, and the wording is different, and the difference does not look very accidental. This is why I ask. (One could reply, "I don't care," which would be fair enough, but of course the question's premise is that someone might care. For example, if one were programming an online chess interface, then one would have to implement the rule the one way or the other. Which would be right?)
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T10:48:35.980Z
Answers.Text: @thb Online chess does not have such problems, because all actions have to be ordered. Usually the interface will disable the option to claim a draw if you mate, or to make a move if you claim the draw. And even in doubt, the requests will hit the server in one order or the other.
Answers.UserDisplayName: Annatar
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T12:26:50.567Z
Answers.Text: If I think about it, there might be one possible scenario after all: a) the program has an option "automatically claim draw if possible" that you have enabled and b) you premoved the mating move. Both actions happen instantly with no client interaction during that move, so which one takes precedence? Depends on the concrete implementation.
Answers.UserDisplayName: Annatar
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T13:57:30.617Z
Answers.Text: Yes, @Annatar. A rules committee should probably consult persons who have programmed the rules into computers, because otherwise they will inadvertently introduce unnecessary, unintended ambiguities of this very kind. Suppose two interfaces with incompatible implementations of the rules were linked. A deadlock might arise, causing the interfaces to cease to work at all.
Answers.UserDisplayName: thb
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2018-01-23T05:53:59.130Z
Answers.LastActivityDate: 2018-01-23T05:53:59.130Z
Answers.UserDisplayName: Herb
Body: <p>This question is for aspiring rules lawyers.</p>
  
  <p>The FIDE's <a href="https://www.fide.com/fide/handbook.html?id=208&amp;view=article" rel="noreferrer">new laws of chess,</a> effective Jan. 1, 2018, patch ambiguities and other subtle problems. I like the new laws. When it comes to game mechanics, I hope that the new laws remain permanently, so may I now ask a totally pedantic technical question regarding a ridiculous but (as far as I know) legal situation?</p>
  
  <p>Under the new laws, suppose that</p>
  
  <ul>
  <li>you have made 50 moves since the last pawn move or capture,</li>
  <li>I have made 49 moves since the last pawn move or capture, and</li>
  <li>it is my turn to move.</li>
  </ul>
  
  <p>Suppose that my 50th move checkmates you. Ridiculously however, suppose that—simultaneous with my move—I claim a 50-move draw. Do I read the laws right: this game is a draw?</p>
  
  <p>Before answering, you might compare law 9.3.1 against law 9.6.2. The new laws are more carefully worded than the old laws were, so I am unsure that the effect in question is a mere unintentional artifact of unfortunate wording. I <em>suspect</em> that the effect might be deliberate, rather.</p>
  
  <p>Can you shed any light in the matter?</p>
  
  <p>Of course, I am not asking why a checkmating player would choose to waive the checkmate in favor of a draw, but am only probing an odd corner of the laws' logic.</p>
  
  <p>See also <a href="https://chess.stackexchange.com/questions/12613/does-checkmate-over-ride-50-move-violation">this related question and answer</a> from before the recent changes in the laws.</p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>It turns out that my question is a duplicate of the linked question, if you look at it the right way.  Morever, an answer to the linked question quotes Geurt Gijssen, an authoritative source. Gijssen answers the question indirectly by answering the inverse question. If I read Gijssen correctly, then a player can indeed claim a 50-move draw while checkmating, <em>and in that case the draw claim would take precedence.</em></p>
  
  <p>Weird, eh?</p>
  
  <p>One could question the relevance of Gijssen's comments, since Gijssen (if I recall) retired before the most recent revision cycle, except that the revision seems to come to address questions Gijssen himself had considered or raised.</p>
  
  <p>This sort of question is interesting if one is, for example, programming a computer interface for online chess play, for the programmer must implement the law in question the one way or the other. Just leaving it ambiguous would probably not be a reasonable option in that context.</p>
  
  <p>I also note that players reading the rule in this very question thread are reaching opposite conclusions regarding the rule's meaning in the present case. Academic questions like this can be significant from a rules-logical perspective (as anyone who has programmed game rules into a computer might verify), even if the situation the question targets might never arise during over-the-board play. No game rule <em>wishes</em> players to reach opposite conclusions regarding its meaning, does it?</p>
  
  <p>Two computer programs with different understandings of the rules might deadlock, if set to play one another, for example.</p>
  
  <p><strong>FURTHER UPDATE</strong></p>
  
  <p>The answers have been really interesting, at least to me.</p>
  
  <p>An actual arbiter in this thread has now persuaded me to the opposite conclusion. He has persuaded me that the checkmate would take precedence, after all.</p>
  
  <p>Unfortunately, one probably cannot but conclude that the rule is ambiguous in the sense that the rule evidently supports reasonable, experienced players to reach opposite conclusions regarding the rule's meaning in this instance.</p>
  
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-01-23T06:38:34.967Z
Comments.Text: No, @HerbWolfe, you are right, after all. My question is indeed a duplicate. Moreover, Geurt Gijssen, who is an authoritative source, is quoted in an answer to the other question. A close reading of the quote implies my answer. I'll now vote to close my own question.
Comments.UserDisplayName: thb
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-01-23T14:04:04.957Z
Comments.Text: How can I merge this question with the original? The answers are good. The answers might be moved over there.
Comments.UserDisplayName: thb
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-01-23T15:25:21.880Z
Comments.Text: I think a moderator would have to do the merge.
Comments.UserDisplayName: Herb
Comments.ContentLicense: CC BY-SA 3.0
Comments.CreationDate: 2018-04-06T07:20:19.387Z
Comments.Text: @HerbWolfe: thb's question then morphs to: how do we request a moderator to perform a merge?
Comments.UserDisplayName: Laska
Tags: <fide><50-move-rule>
Title: Simltaneous checkmate and draw claim on the 50th move
ThreadText: # Simltaneous checkmate and draw claim on the 50th move
  
  (Asked by: username_0 on 2018-01-23)
  
  This question is for aspiring rules lawyers.
  
  The FIDE's [new laws of chess,](https://www.fide.com/fide/handbook.html?id=208&view=article) effective Jan. 1, 2018, patch ambiguities and other subtle problems. I like the new laws. When it comes to game mechanics, I hope that the new laws remain permanently, so may I now ask a totally pedantic technical question regarding a ridiculous but (as far as I know) legal situation?
  
  Under the new laws, suppose that
  
  * you have made 50 moves since the last pawn move or capture,
  * I have made 49 moves since the last pawn move or capture, and
  * it is my turn to move.
  
  Suppose that my 50th move checkmates you. Ridiculously however, suppose that—simultaneous with my move—I claim a 50-move draw. Do I read the laws right: this game is a draw?
  
  Before answering, you might compare law 9.3.1 against law 9.6.2. The new laws are more carefully worded than the old laws were, so I am unsure that the effect in question is a mere unintentional artifact of unfortunate wording. I *suspect* that the effect might be deliberate, rather.
  
  Can you shed any light in the matter?
  
  Of course, I am not asking why a checkmating player would choose to waive the checkmate in favor of a draw, but am only probing an odd corner of the laws' logic.
  
  See also [this related question and answer](https://chess.stackexchange.com/questions/12613/does-checkmate-over-ride-50-move-violation) from before the recent changes in the laws.
  
  **UPDATE**
  
  It turns out that my question is a duplicate of the linked question, if you look at it the right way. Morever, an answer to the linked question quotes Geurt Gijssen, an authoritative source. Gijssen answers the question indirectly by answering the inverse question. If I read Gijssen correctly, then a player can indeed claim a 50-move draw while checkmating, *and in that case the draw claim would take precedence.*
  
  Weird, eh?
  
  One could question the relevance of Gijssen's comments, since Gijssen (if I recall) retired before the most recent revision cycle, except that the revision seems to come to address questions Gijssen himself had considered or raised.
  
  This sort of question is interesting if one is, for example, programming a computer interface for online chess play, for the programmer must implement the law in question the one way or the other. Just leaving it ambiguous would probably not be a reasonable option in that context.
  
  I also note that players reading the rule in this very question thread are reaching opposite conclusions regarding the rule's meaning in the present case. Academic questions like this can be significant from a rules-logical perspective (as anyone who has programmed game rules into a computer might verify), even if the situation the question targets might never arise during over-the-board play. No game rule *wishes* players to reach opposite conclusions regarding its meaning, does it?
  
  Two computer programs with different understandings of the rules might deadlock, if set to play one another, for example.
  
  **FURTHER UPDATE**
  
  The answers have been really interesting, at least to me.
  
  An actual arbiter in this thread has now persuaded me to the opposite conclusion. He has persuaded me that the checkmate would take precedence, after all.
  
  Unfortunately, one probably cannot but conclude that the rule is ambiguous in the sense that the rule evidently supports reasonable, experienced players to reach opposite conclusions regarding the rule's meaning in this instance.
  
  **Tags:** fide, 50-move-rule
  
  > **Comments:**
  > **username_0**: No, @HerbWolfe, you are right, after all. My question is indeed a duplicate. Moreover, Geurt Gijssen, who is an authoritative source, is quoted in an answer to the other question. A close reading of the quote implies my answer. I'll now vote to close my own question.  
  > **username_0**: How can I merge this question with the original? The answers are good. The answers might be moved over there.  
  > **username_1**: I think a moderator would have to do the merge.  
  > **username_2**: @HerbWolfe: thb's question then morphs to: how do we request a moderator to perform a merge?  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_3 on 2018-01-23. Score: 5 | Accepted answer
  
  I would let the checkmate stand but the true answer is that it does not matter. The player has the right to offer a draw at any time and the claim according to article 9.3 is also a draw offer. You are concerned with a peculiar situation where player A wants a draw and does not want to win, for whatever reason, while player B does not want to draw (even at the cost of a loss). Therefore, the question you really ask is whether claiming a draw according to article 9.3, if the intended move delivers a checkmate, can secure you the draw. Abstracting away from the possibility that you can choose any other legal move and claim on that basis, the answer to that question is that yes, there is a way.
  
  You can claim the draw as you proposed and if the arbiter rejects the claim because the checkmate stands then you simply let your time run out and the game is a draw because the opponent cannot checkmate you by any series of legal moves. This is since you have committed to play the checkmating move thus there is no way how the opponent could checkmate you as they are going to be checkmated on next move. A catch is that not all arbiters may be comfortable with this interpretation and they may declare the game lost for you even though they shouldn't. But this situation will never happen anyway, right? It is purely of academic interest.
  
  I would let the checkmate stand for two reasons.
  
  1. Consider this variation on your question, you claim the draw as you proposed but the intended move does not deliver a checkmate but rather captures a pawn. Again, as you point out, the move has not yet been made, hence, the pawn is never captured. Still the claim should be rejected. To assess the validity of the claim you need to consider the position as if the move had been played. I would apply this reasoning to the checkmate situation. If there is a checkmate after the intended 50th move, the validity of the claim cannot be assessed since the game will have finished. Of course, you can choose another move and claim the draw.
  2. Article 9.6.2 explicitly says that the checkmate takes precedence, therefore, I would apply it to article 9.3.1 too (not 9.3.2 since the game would have already finished once the checkmate is on the board). The crux is whether article 9.3.1 omits to mention this precedence intentionally. If this was so then what would the intention be? The intention would have to be to allow the player to secure a draw instead of the win and this is pointless as I explained earlier. Therefore, this difference in the wordings is not intentional, in fact, article 9.3.1 does not require it while article 9.6.2 does. In the situation described in 9.6.2 the player does not have the option not to claim, the amendment protects the stronger player here.
  
  It does not really matter though. Imagine 50 moves without a capture or moving a pawn have already been played. Then the player can either claim according to 9.3.1 as you proposed or they can claim according to 9.3.2 even though they could deliver a checkmate next move. In the latter case it is an unambiguous draw. It does not make much sense to obtain to different results depending on which way you claim the same thing (yes, I am undermining my earlier arguments) but either way you get something out of it that does not make much sense. But again, no one forces you to claim a draw with a checkmating move. In fact, this may trigger a punishment according to article 12.9 for putting chess in disrepute.
  
  I am afraid you misunderstand Geurt Gijssen's answer. He did not answer your question at all, he said that the player having the move would not make the claim, because it does not make sense, and the opponent is not allowed to make the claim, because it is not their move. It does not follow from his answer that he would agree with the claim if the player really made it.
  
  > **Comments:**
  > **username_0**: Your whole answer is interesting to me (even though I have voted to close my own question). I especially like your point regarding article 12.9. If you want to know, I was thinking of someone like the programmer of an online interface for chess play. They're writing a program, and the program cannot know anything about article 12.9, yet regarding article 9.3, the program's logic cannot but be coded the one way or the other.  
  > **username_0**: Your IA title lends weight to your answer. Let me *accept* your answer for this reason.  
  > **username_0**: Who *downvoted* this answer? One can disagree with the answer's conclusion, but one can hardly characterize the answer as unreasonable or ill informed. That was an odd downvote.  
  
  ---
  
  ### Answer by username_4 on 2018-01-23. Score: 8
  
  The Laws of Chess say:
  
  > 9.3 The game is drawn, upon a correct claim by the player having the move, if
  >
  > a) he writes his move on his scoresheet and declares to the
  > arbiter his intention to make this move, which shall result in the
  > last 50 moves having been made by each player without the movement of
  > any pawn and without any capture, or
  >
  > b) the last 50 consecutive moves have been made by each player
  > without the movement of any pawn and without any capture.
  
  So you don't claim the draw WHILE you checkmate but BEFORE you make the checkmate move. Therefore there is no checkmate, but the game is drawn.
  
  If you don't claim the draw but execute your checkmate move, your opponent cannot claim a draw by 9.3.b) because the game is finished by your checkmate.
  
  > **Comments:**
  > **username_0**: I like the answer. Still, from experience with other games, I observe that stretching the mere accidental *wording* of a rule to cover situations the rule's writer did not consider is a practice that has never, as far as I know, produced agreement among players as to what the rule actually means. If players do not agree to meaning, then, in a sense, you don't even have a rule. I do not assert that you have stretched anything, of course, but see: another player has in good faith given an opposite answer in this very thread. So, maybe the FIDE could word the rule better?  
  > **username_4**: The rules are very clear. Rule 9.4 states:  "If the player touches a piece as in Article 4.3, he loses the right to claim a draw under Article 9.2 or 9.3 on that move." So you cannot claim a draw after or "during" the checkmate move. Either you claim a draw before touching a piece or you make the checkmate move and win.  
  > **username_0**: I have noticed that, in discussion of game rules, "clear" means "clear" but "very clear" invariably means "not clear at all," unfortunately. One must allow adequate scope for that reasonable, informed readers can read the same words and yet (to the mutual surprise of each) perceive opposite semantics therein. When reasonable, informed readers (including you and others in this thread) do perceive opposite semantics, does this not reveal a flaw in the words?  
  
  ---
  
  ### Answer by username_1 on 2018-01-23. Score: 3
  
  It appears that 1.4.2 and 5.1.1 on that page would take precedence.
  
  > 1.4.2 The opponent whose king has been checkmated has lost the game.
  >
  > 5.1.1 The game is won by the player who has checkmated his opponent’s king. This immediately ends the game, provided that the move producing
  > the checkmate position was in accordance with Article 3 and Articles
  > 4.2 – 4.7.
  
  > **Comments:**
  > **username_0**: Except that the checkmating move has not yet been made? I would not be asking except for the difference in wording between 9.3.1 and 9.6.2 in the new laws.  
  > **username_0**: I have never thought that rules should be read so literally that one extracts a meaning opposite to that which the rules' writer intended. However, in this case, you have 9.3.1, and you have 9.6.2, and the wording is different, and the difference does not look very accidental. This is why I ask. (One could reply, "I don't care," which would be fair enough, but of course the question's premise is that someone might care. For example, if one were programming an online chess interface, then one would have to implement the rule the one way or the other. Which would be right?)  
  > **username_5**: @username_0 Online chess does not have such problems, because all actions have to be ordered. Usually the interface will disable the option to claim a draw if you mate, or to make a move if you claim the draw. And even in doubt, the requests will hit the server in one order or the other.  
  > **username_5**: If I think about it, there might be one possible scenario after all: a) the program has an option "automatically claim draw if possible" that you have enabled and b) you premoved the mating move. Both actions happen instantly with no client interaction during that move, so which one takes precedence? Depends on the concrete implementation.  
  > **username_0**: Yes, @username_5. A rules committee should probably consult persons who have programmed the rules into computers, because otherwise they will inadvertently introduce unnecessary, unintended ambiguities of this very kind. Suppose two interfaces with incompatible implementations of the rules were linked. A deadlock might arise, causing the interfaces to cease to work at all.  
  
  ---
  
  