Posted 2015-January-25, 23:18
I probably wrong, but it is interesting problem.
Couple of issues. How is it that South finds a bid over 3NT or 4NT?
Second, I am assuming the spade JACK won trick one since you didn't say which spade was played.
AT IMPS I will play for a heart split of 3=3, 4=2, or 5=1 with singleton jack. The basic line seems to cash heart king, cash two clubs, ruff a club with heart queen, cross to spade ace and play trumps from top down. If the jack drops in two rounds, you have 5H, 3S, 2D, 2C and 1C ruff for 13 tricks. If the heart jack does not fall, play a third round of hearts. You lose the jack but you have control if hearts are 3-3 or 4-2. Now you win 4H, 3S, 2C, 1 club ruff and 2D for 12 tricks. If the heart jack is singleton, you will lose a heart but still avoid the risk of a diamond loser. Cash four heart winners, cross to the diamond Ace, pitch a diamond on the spade king, win 4 H. 3S, 2C, 1C ruff, 2D... they may ruff your third spade, or second diamond, but if they do, you get a fifth heart.
Chances of 13 tricks is not great (need Jx of hearts, which is something like 16%, but chance for 12 tricks is 86% or so,
The chances for 13 tricks is, of course, higher if you don't ruff a club, but it increases the chances you will go down. If hearts are 3-3 or heart jack is doubleton, you have 2C, 5H, 3S, and you can always get 4 diamonds for 12 tricks, 13 if you guess right in diamonds. The chance for 13 tricks is much greater here (roughly 50%) once hearts behave. But your trick total could collapse to below 12 if you have a heart loser (you know have 4 hearts, 2D, 2C, 3S for only 11 tricks), so getting diamonds right is required to make the slam. The matchpoint problem however is not getting 13 tricks here, it is that most people in slam will be in 6NT rather than the 5-2 heart fit or in 6 diamonds. IF they take 13 tricks in diamonds, just making 6 hearts is good enough, if they take 13 tricks in Notrump there is no way you can beat them, They have (in NT) 3H, 3S, 4D, and 2C against any lay of the cards, and if hearts break of they find the diamond queen, they have 13 tricks. So I guess I will take the IMP line at both matchpoints and IMPS without worrying about if it to risky to avoid the high probability of success line to make just 12 tricks.
--Ben--