[pescetom]

MP

The hand

This was a 30%, instead of 57% for +1.

Any idea what was going on at trick 3?

[thorvald]

Looks resonable to me if playing a bit safe - wrong with singleton Ten, but right with a small singleton (3 times as likely), Also right with a singleton K

[smerriman]

I have a feeling GIBson doesn't take into account IMPs vs MPs, choosing between lines based on which makes the contract more often (Suitplay says ace is best at matchpoints, 9 is best at IMPs).

If someone can think of a made up deal which would prove/disprove this, I can test that theory..

[thorvald]

smerriman, on 2022-August-19, 15:58, said:

I have a feeling GIBson doesn't take into account IMPs vs MPs, choosing between lines based on which makes the contract more often (Suitplay says ace is best at matchpoints, 9 is best at IMPs).

If someone can think of a made up deal which would prove/disprove this, I can test that theory..

I think you are right. On the other hand we have seen deals where GIB risk giving the contract based on extra undertricks, but perhaps it is different in declaring and defending

[smerriman]

Actually, ignore that, just tested and it definitely has different MP / IMP strategy like I originally thought.

Will keep digging..

[smerriman]

Actually, I'm not even sure there's even anything fundamentally wrong here. The two lines were close to begin with, and with GIB interpreting 2♠ as spades and a minor, is the 9 really worse?

[thorvald]

smerriman, on 2022-August-19, 16:58, said:

Actually, I'm not even sure there's even anything fundamentally wrong here. The two lines were close to begin with, and with GIB interpreting 2♠ as spades and a minor, is the 9 really worse?

Good point, as that changes the odds for single ♣ in east, and the the 9 is the correct card

[pescetom]

thorvald, on 2022-August-19, 15:42, said:

Looks resonable to me if playing a bit safe - wrong with singleton Ten, but right with a small singleton (3 times as likely), Also right with a singleton K

If E has a singleton, then isn't it K or T 50% after W plays the 2?

[thorvald]

pescetom, on 2022-August-20, 06:52, said:

If E has a singleton, then isn't it K or T 50% after W plays the 2?

Nope, as the 2 is a small card odds aren't changed

[pescetom]

thorvald, on 2022-August-20, 08:36, said:

Nope, as the 2 is a small card odds aren't changed

Fair enough, so 40% then.


Of the 23 pairs that made overtricks, all but two of the human declarers played the A on first clubs trick (several received the T as lead by a robot opponent).
Curiously, the only time a robot declarer chose the A rather than 9 was when a human opponent had interfered 2◇ multi showing an undisclosed 6 card major (which the robot declarer presumably takes as diamonds).