[helene_t]

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Some GIB idosyncracies are well-known bugs in the bidding DB.
Some are not well-known but affect convoluted auctions that don't come up often so who cares.
Some are general weaknesses of the DD sim approach nothing to do.
Some are plausible statistical flukes in the DD sims.

But what is this? It's not like the explanation of my double looks like GIB had forgotten that I opened 1NT. Can 4♠ really be favoured by DD sims for any possible (I am not saying reasonable, just possible) interpretation of my bidding?

[johnu]

When were you playing? Sometimes GIB switches to lunchtime bridge mode where it plays like a newbie playing in the lunchtime game at work.

[smerriman]

4♠ is basic GIB's bid. So the first question is whether advanced GIB actually simulated at all.. you'd think it should in this scenario.

Though I tried to simulate myself through dealer.php and every time it generated a million hands, it would often come up with 0, sometimes 1 hand which matched the bidding (after 15 seconds). Don't know how it works on GIB's side, but maybe it failed to find enough matches in whatever time it has available and so reverted to the book bid..

[johnu]

smerriman, on 2022-February-10, 22:17, said:

Don't know how it works on GIB's side, but maybe it failed to find enough matches in whatever time it has available and so reverted to the book bid..

I thought GIB usually passed when it couldn't figure out what to do. That approach would be a winner here.

[helene_t]

My impression is that GIB has problems with auctions that are impossible (someone must have misbid) because the sim set is empty, and then it defaults to some stupid mechanistic rule maybe.

Jack has a relaxation mode for such situations where it gradually makes the other three players less disciplined until the sim set becomes non-empty (and when playing against humans who have a track record it will assume the one who has the worst discipline records to be the one who has lied) but I don't know if GIB does something similar.

[johnu]

smerriman, on 2022-February-10, 22:17, said:

Don't know how it works on GIB's side, but maybe it failed to find enough matches in whatever time it has available and so reverted to the book bid..

It's hard to see how the "book" bid could be 4♠ (or actually any bid with this hand except pass opposite a 1NT opener) with closer to a yarborough than anything else. On the other hand, the 1NT opener may have an opposing 4 level contract beat in hand with quick tricks, notwithstanding holding a 100% certain diamond trick which probably has no offensive value in 4♠.

[smerriman]

johnu, on 2022-February-11, 18:56, said:

It's hard to see how the "book" bid could be 4♠

You know as well as I do that all doubles are takeout for GIB, and that 'book' doesn't mean human-approved, just a result of a rule. So not hard to see in the slightest.

[johnu]

smerriman, on 2022-February-11, 20:24, said:

You know as well as I do that all doubles are takeout for GIB, and that 'book' doesn't mean human-approved, just a result of a rule. So not hard to see in the slightest.

It's still unbelievable

[pescetom]

GIB System Notes said:

Takeout doubles to 4♥

Admittedly a crappy agreement if applied when partner has limited strength and distribution to 15-17 balanced and spades