So, I've encouraged you to make penalty doubles of no trump overcalls. Now a cautionary tale against weak NT openings. You want to have a penalty double available when defending against Weak NT openers, but must be sensible with its use. August 25, 2018 at Adventures, Hand #19, West (you) held: ♠K42 ♥A64 ♦AQ753 ♣Q9. On your right, South opened a 12-14 no trump. Our West chose to double. The double is penalty oriented—showing a hand with the top of notrump bidders range or more. This is technically correct (15 HCP), but I don't like the ♣Q9. I like the five diamonds, but am lacking interior spots.
North passed, which systemically asks partner to redouble either to play 1NT redoubled, the intention here, or to show a weak hand with two non-touching suits with hope of escaping 1NT* to a eight card fit at the two level—a so-called “runout sequence”. East passed, though with East's hand, ♠Q9853 ♥10973 ♦J4 ♣72, I would have run to 2♠. I do NOT play Systems On when partner makes a penalty double of their NT, because I believe we need to be able to run from the double with a horrible hand, into ANY five card suit—including 2♣ and 2♦. South might find the double of 2♠, which can be set two tricks, or might not… However, East passed, South duly redoubled. West panicked and bid 2♦ and North brought out the red card. (If East does run to 2♠ now, South will definitely bring out the red card.)
North led the ♠10. South took the ♠A and returned the ♠7 (suit preference for hearts—the higher side suit—the ♠J is too valuable to signal with). North duly ruffed the spade and returned a heart. That went to South's ♥Q and West's ♥A. Poor West suffered greatly, losing two clubs tricks, two heart tricks, the ♠A, two spade ruffs, and the ♦K. That was down three, vulnerable, for −800 on a board where N/S will NOT be able to get to their game. Then again 1NT** collects two overtricks both double dummy and readily in practice, for +960 to N-S, also not a pretty score for E-W.
Incidentally, you better have a discussion with your partners about how much is enough to sit for a penalty oriented double of either a strong OR a weak NT bid! With balanced hands, I always sit. With a long suit, I run with 4 or fewer HCP.
Hand #9 was an interesting one. You've heard the mantra: slams are based on tricks (long suits) and controls (Aces and Kings). Ruth Ng had the control-rich North hand and opened 1♥ with ♠Q7 ♥AK653 ♦K98 ♣KQ8. She heard me bid 2♦—which usually shows a five card suit and is a game-forcing bid. She elected to bid 3♦ and await developments. I then bid 3♠, showing a spade stopper for NT which has to be Ace or King as she is looking at ♠Qx. Ruth could have signed off with 3NT, but she knew we should have 30 HCP or more between us and that I cannot have more than two hearts, so no heart losers. She does not have more than one spade loser (since I have promised a high spade), so slam is still a possibility.
So, Ruth bypassed 3NT with 4♣—a “concentration of values” bid. It could be showing ♣A or the ♣K—or ♣KQ as in this case. This is a clear slam try since she has gone past 3NT. I then bid 4♠. That should show more stuff in spades and a willingness to cooperate with her slam seeking. At that point, Ruth bid 6♦. [We don't play a lot, so 4NT could be ambiguous—possibly might be deciding to play NT after all. I don't think we've discussed whether 4♦ would be Minorwood in this situation. When in doubt, don't do anything that could confuse your partner! Our hands were:
♠Q7 ♥AK653 ♦K98 ♣KQ8
♠AK10 ♥72 ♦AQ1062 ♣1076
The lead was the ♣A which made things easy. 6NT would be a very pushy slam, although one super-aggressive pair bid it. 6NT requires the ♣A onside and favorable diamonds, either a 3-2 split or a singleton the ♦J, altogether about a 43% chance (50% × 87%). The 6♦ slam has the extra chance that if the ♣A is offside, it will be possible to pitch a club on the third round of spades and then ruff the third round of clubs in dummy. This requires spades to hold up three rounds (80% chance) and clubs to hold up either three rounds (62% chance) or twice (31%) so long as the defender short in clubs does not hold the ♦J, an aggregate chance of about 60%.
I think the auction showed good analysis by my partner. The other 11 pairs in the room were playing 3NT, making either 5 or 6.
What is the probability of 6♦ making? This is tricky to calculate. If the opponents will let you combine the your chances, 50% when the ♣A is onside with the 30% = (50% × 60%) extra chance when it is offside, the overall probability of success is about 80%, much better than the 6NT slam. But clever opponents can deny you this addition. Suppose you lead a club to dummy and an honor holds. If you know or strongly suspect the RHO is the sort to take their ♣A, slavishly “covering an honor with an honor”, you will know which option to pursue next. But suppose LHO is clever enough to hold off, perhaps thinking to give you a guess in the suit when you lack the ♣J and have three or more clubs. Now you must commit to one option, and the most probable one is the 50% chance that LHO has the ♣A. So the chance are between 50% and 80%. In most fields, you'll have at least a 70% chance, significantly better than the 6NT slam.
Note: when the opponents have a lot of cards in a suit and their bidding does not indicate a bad break, favorable breaks are very likely. For example, an eight card suit splits 4-4 (32.7%) and 5-3 or 3-5 (2 × 23.6% = 47.2%) of the time for a total probability of 80% for a generally favorable break. Seven cards will split 4-3 or 3-4, 62% of the time and 5-2 or 2-5, 31% of the time.