[thorvald]

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Lead: ♠K

How would you play this? Would it change anything if South was Robot?

Now when simulating this I assume the bot places 5♠ in south, but I have seen the Robots frequently overcall on 4-card majors (But haven't found the rule for doing it), so how is the actual simulation done?

[smerriman]

thorvald, on 2022-August-16, 17:53, said:

so how is the actual simulation done?

Nobody knows. I recall a very old thread - can't find it now - where one of the GIB developers gave some very basic insights into the simulations (eg saying that GIB includes some hands that don't match the bidding to catch some psychs), but that he wasn't at liberty to reveal any more details.

The old Windows version I'm using lets me see what hands the robots simulate when defending though, so I'm trying to reverse engineer the logic a bit.. will let you know what I end up with.

[thorvald]

When simulation the West hand on this deal

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I know that using double dummy analysis declarer will always find ♥Q, so this might be one of the situations where all plays are losing, so it really doesn't matter.

But still I suspect there are som rules about how to select a random card :-)

Switching ♣Q and J and the ♥-shift might be giving away the contract

[smerriman]

thorvald, on 2022-August-17, 05:13, said:

I know that using double dummy analysis declarer will always find ♥Q, so this might be one of the situations where all plays are losing, so it really doesn't matter.

That's exactly what's happening here.

When I get it to simulate from 100 hands, virtually all of them give South a normal 16-17 point hand, and concludes that every card is identical.

Three or four of the 100 it assumes South psyched, and that's what primarily breaks the ties. It comes up with different leads every time I try as a result; once it led a heart because one of the psychs was:

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and a heart was the only continuation double dummy says would defeat the contract.

[thepossum]

I'm curious. I've rarely seen the bots overcall with 4 of anything??

I keep trying to work out GiB's leads but I would place KQJxx with South and 8+ points (possibly fewer if nice and distributional)

It looks reasonably straightforward

Sorry I am with the OP - the thread changed