In the board position both knights can move to e4. To distinguish which knight moved one would normally write Nce4 or Nfe4. However in this special situation only Nce4 is check.

Would it be sufficient here to write Ne4+ (meaning Nce4) only (i.e. without the "c" but with "+"), as Nfe4 would not be check?

By sufficient I mean whether there are any (FIDE or other organization) laws regarding such issue.

8/8/5N2/8/3k4/2N5/8/B3K3 w - - 1 1
  • I would point out that the original question says nothing about it being a tournament, let alone FIDE governed...just whether it solves the ambiguity problem. – PhishMaster Sep 12 '19 at 16:33
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    @PhishMaster: I am aware that it solves the ambiguity. I was wondering whether such situation is regulated. I edited the question to make it more clear. – user1583209 Sep 12 '19 at 18:35
  • Even if writing Ne4+ were technically illegal by FIDE laws (I don't know whether it is or not), in practice you would suffer no penalty in a FIDE rated tournament for doing so. – Inertial Ignorance Sep 13 '19 at 1:37
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    I look forward to the followup question, "Ambiguity in notation resolved by !". – Micah Sep 14 '19 at 3:58
  • @Micah 47. f5 Q!!. Perfectly unambiguous. I mean of course that only move which avoids the mate in 26. – leftaroundabout Sep 14 '19 at 9:57

Would it be sufficient here to write Ne4+ (meaning Nce4) only (i.e. without the "c" but with "+"), as Nfe4 would not be check?

It depends on exactly what you mean by "sufficient". By "normal" definitions of "sufficient" the answer is obviously "yes". "Ne4+" disambiguates and leaves the human reader in no doubt which knight was moved.

However it doesn't work in FEN diagrams. You need to specify Nce4 to get it to work. So, then the answer would be "No".

The FIDE Laws of Chess describe how you should annotate your games in Appendix C and that does not allow for using check as a way of disambiguating between two different pieces of the same type moving to the same square. However there is no penalty specified for mistakes. It is up to the arbiter to decide and that will only happen if it is noticed.

In real life the most that might happen is that if the games are transcribed for sending to FIDE or for publishing the player might get a scolding from the arbiter tasked with this chore, but this is extremely unlikely in this case and would happen long after the game is completed.

Mistakes far worse than this happen all the time and the only comeback from the arbiters is when the scoresheet is completely illegible or grossly incomplete. Vigilant arbiters will notice these misdemeanors during the game and warn the player concerned to mend their ways.

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  • Thank you for discussing various fields including FEN. I am aware that this example is a bit contrived and very rare. – user1583209 Sep 12 '19 at 18:38
  • It can be seen in old notation -- several times the last month I've looked at a chess problem solution that basically boiled down to 'R+ or 'R#', but where it was left to me to find out which rook, and which of the available moves actually did lead to mate. Unambiguous, yes, but it gives up clarity. (And if the reader makes a mistake, or gets confused, it puts the blame for that on that reader. Clarity and perspicuity should be goals, even in the face of technical redundancy.) – user18412 Sep 14 '19 at 6:16
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    One definition of "sufficient" would be whether it would be acceptable as a sealed move in an adjourned game, I think. – D M Sep 14 '19 at 11:46
  • "However it doesn't work in FEN diagrams" FEN is a system for specifying board positions; it has nothing to do with moves. – David Richerby Sep 14 '19 at 13:58
  • Now what if the other knight was also on the C file, e.g. at c5? And what if there was, say a queen at a7 (unlikely to be another bishop since they'd both be on black spaces)? In that case moving either knight to e4 would result in a check, so even the precise Nce4+ is still ambiguous. You'd have to write something like Nc3e4+ or Nc5e4+ in order to distinguish them? – Darrel Hoffman Sep 14 '19 at 17:50

The FIDE Laws of Chess 2018 are unambiguous: you should write Nce4, and the + sign is optional and not disambiguating. Ne4+ is not sufficient.

Appendix C (algebraic notation), article C.10 basically tells you to write Nce4 to distinguish it from Nfe4. It does not mention check or other ways to disambiguate.

Article C.13 notes that writing "+" to indicate check is optional, which also implies that it does not serve to distinguish between a Ne4 that checks and one that doesn't.

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    While I agree with the first two paragraphs, the last paragraph isn't relevant. Just because something optional does not mean that it can't be used to distinguish. It means that Ne4 is still ambiguous (after all it could mean either Ne4 or Ne4+ since the plus is optional), but Ne4+ is definitely unambiguous regardless of the optionality of the +. – orlp Sep 13 '19 at 13:33

I would say yes, but it certainly does not hurt to write Nce4+. What is one extra character among friends? :)

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  • Before you downvote this, please realize that the question was edited later to specify that it meant per rules. It did not originally. – PhishMaster Sep 20 '19 at 13:35

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