heart76, on 2018-December-19, 04:24, said:
I do not normally ask this, and no hard feelings irrespective of what you will say, but can the TD take a look at GIB defence on board 14?
The difference between the 2 hands is the first card played from dummy from a doubleton, resulting in a 10 IMP swing which is IMHO totally unfair
Ok, GIB has its limits, but depriving the long spades from a side ace is above and beyond.
I dealt 500 hands which matched these rules:
- North has K93 in spades
- North has either 4 hearts, or 5 hearts and less than 11 total points (didn't bid 2
♥ directly)
- North has less than 4 diamonds (wouldn't bid 3NT)
- North has between 11 and 18 HCP (going by definition)
Note North will bid 3NT even with four low hearts, so you can't assume any honors there.
The results:
In 63 cases, partner had the club ace. Leading the spade beats 3NT, while leading the heart Ace allows it to make. Heart Ace costs 10 IMPs.
In 112 cases, we can cash the setting tricks in hearts, gaining either 11 (53 cases) or 12 (59 cases) IMPs.
In 266 cases, cashing the heart saves an overtrick, gaining 1 IMP.
In 50 cases, we can save two overtricks by cashing the heart, gaining 2 IMPs.
In 9 cases, cashing the heart Ace costs an overtrick, losing 1 IMP.
Overall, playing the heart Ace is 2.04 IMPs better than playing a spade.
Based on the frequencies in this simulation, suppose GIB deals 20 hands before leading at trick 3. 8% of the time, the results will say to lead a spade, and 92% of the time the results will say to lead a heart.
So if you're saying the heart lead is a bug; that's clearly not right. If you're saying the spade lead is a bug, well, that will happen 8% of the time (adjust based on the number of deals); that's not a bug, just how simulations work.
If you're saying both tables should have led a heart, then it's plausible that some code could be built in to synchronise the random seeds in this case where the deals have gone back to equal. But this sounds complex, especially when there are probably similar situations where you wouldn't want to.