[Cyberyeti]

Stephen Tu, on 2020-August-30, 16:53, said:

I tested, GIB will overcall on KQxxx xx Kxx xxx at a bidding table.

I think nearly everyone will overcall holding DAK as West which hasn't been ruled out at all. I think very many would overcall with the dA without the DK. Certainly with some bit of shape like KQxxx xxx Axxx x, no? And I think a lot would still overcall with just the DK and some shape, maybe dropping the 5332 flat ones.

So I don't think there's much slotting the CK into the West hand, much less than you think, apparently.
It would be different if East had laid down a diamond honor to start with, of course.

In that case you don't have the inference agaist GIB. I don't think many people in clubs here would overcall with that first hand, and it's quite a fortunate lie of the cards that you can't take 800 out of 1♠ as it is.

[Stephen Tu]

Cyberyeti, on 2020-August-30, 17:02, said:

In that case you don't have the inference agaist GIB. I don't think many people in clubs here would overcall with that first hand, and it's quite a fortunate lie of the cards that you can't take 800 out of 1♠ as it is.

My main point is that just ruling out the first hand isn't enough to slot CK with West. SKQ DAK no CK is overcalling 100%, and many SKQ DA no CK are overcalling also.

Even if you could take 800 out of spades, the thing is people aren't going to trap pass with Axx spades and 6 hearts, or AJT spades and 6 hearts, or really any hand with only 3 spades, and opener doesn't reopen dbl with 3+ spades, so it's really hard to punish light 1 level overcalls as often as they theoretically could be if NS were cheating.

[Zelandakh]

Stephen Tu, on 2020-August-30, 15:18, said:

Assuming spades are 5-2 and the first club isn't ruffed, the ruff finesse is a little bit less than 6% better than trying to ruff out the K; the relevant combos are 17.59% vs 11.65%.

West is not playing DD though is it? What are the combined chances of playing the ♣Q and ruffing if West does not cover, then crossing in trumps and ruffing low clubs?

[Stephen Tu]

Zelandakh, on 2020-August-30, 18:34, said:

West is not playing DD though is it? What are the combined chances of playing the ♣Q and ruffing if West does not cover, then crossing in trumps and ruffing low clubs?

Hmm I guess I am used to human opps who will never cover with West, didn't really consider robots are so bad that they maybe always cover. I guess robot is catering to line taken with CJx doubleton in North? I am not well versed in anti-bot play.

Looking at the math carefully, if we assume 100% cover from West, it seems it's *still* better to finesse East for CK, it looks like 57% and change vs 53% and change, picking up west CK (5c or fewer) and east CKxx/CKx/CK.
If west will overcall freely w/o CK basically there are a lot of CKxxx(xx) where have to hook East.

I did some testing and on my old PC GIB, it seems West always covers CQ, East only covers CJ with CKx but not with CKxx or CKxxx. So my initial analysis was probably wrong, and supposed to go down on this hand hooking East.