gnasher, on 2012-December-22, 16:31, said:
(1) Yes, we give him nine tricks. His claim told us what he would do if the defence cashed another diamond. He omitted to tell us what he would do if they didn't, so we consider what the normal lines of play are and see if any of them fail. None of them do. He's allowed to take the finesse because it would be irrational not to do so.
TFLB L70E1 said:
The Director shall not accept from claimer any unstated line of play the success of which depends upon finding one opponent rather than the other with a particular card, unless an opponent failed to follow to the suit of that card before the claim was made, or would subsequently fail to follow to that suit on any normal line of play, or unless failure to adopt that line of play would be irrational.
For the purposes of Laws 70 and 71, normal includes play that would be careless or inferior for the class of player involved
The
♥K is a particular card but, arguably, if there were several
♥ missing, then failure to finesse might be deemed irrational... unless you rate declarer is a rank
beginner. IMO, another intriguing question is whether "then I have eight top tricks" can be treated as a claim statement. And, if so, whether the director should permit declarer to modify it, later.
gnasher, on 2012-December-22, 16:31, said:
(2) When he has Axxx opposite KJxx, we don't let him take the finesse, because playing the suit from the top is a "normal" line.
Under current law, IMO, it seems that the director should rule against declarer, whether the finesse works or not, unless
♥Q is
on-side and
doubleton... but what if you rate declarer as
world-class?
Again, I suppose such rulings are a question of trying to interpret the law, taking into account how well you know the players.