[iandayre]

http://tinyurl.com/oevd7ue

ACBL Robot tourney, MP Classic. (Robot declares when appropriate)

I reached the normal contract of 3NT, recognizing that the 2S rebid doesn't promise 6, and by taking the risk (only with robots of course) of making the natural rebid of 3D. So after a club to the Ace and a club back, any sensible declarer would lead a S to the J, guaranteeing at least 9 tricks with a chance for as many as 11. But for reasons unfathomable to me, it played a S to the 9, losing to the Ten. Clubs were set up and 8 tricks were the limit.

What possible reason would GIB have concocted for taking this bizarre finesse? I considered the MP angle, perhaps the robot perceived us behind the field for not being in Spades? Doesn't make sense with that lead and continuation. Robots declaring 4S all played a S to the J and took 11 tricks - the same 11 available in NT with the normal line of play. All in 3NT - a slightly larger number - failed as happened at my table.

So can anyone seriously explain why this happened?

[Stephen Tu]

Small sample size error, maybe also combined from some error from biasing based on lead vs. NT vs. suit? Playing for the drop, in terms of MP score assuming everyone is in game, is actually only about 1% better than taking the hook. Maybe it isn't dealing enough hands to reliably tease out this difference?

Probably GIB needs some sort of function that gives more of a "make the damn contract" bonus, at MP, assuming something weird may happen at a few tables so it shouldn't be so blase about risking going down. I think it already has one, but maybe it needs to be tweaked higher. Same deal for cashing aces vs. slam, "beat the damn contract" bonus, vs. going for extra undertricks.

[johnu]

I don't think anybody can explain some of the GIB plays. As you know, you can 100% avoid bad GIB declarer plays by playing in the human declares tournaments. I have not played in a tournament where the robot can declare since the human declare tournaments were started because it eliminates a major source of irritation caused by inexplicable (awful) GIB declarer play.