Interesting evaluation

[thorvald]

[hv=pc=n&n=s53haq43dqt7643ck&d=e&v=e&b=6&a=p2cd2dp2np3cp3dp7dppp]133|200[/hv]

 

The explanation to 7♦ is 6+♦ and 13+ total points

 

Now I assume that the bot knows we have a ♦-fit, so it can add 1 point for the doubleton ♠, and 3 points for singleton ♣, but then there shuold be deducted some for the singleton ♣.

 

Now the other bots just cashed the ♣A, making me think there should be some kind of ace checking before bidding a grand with 36+ total points

[thorvald]

I just checked the hand against a 2N-opening, and now the bot will bid 4♦ (5+♦, 11-20 total points) after the 3♦-response, so it could be a generic rule overriding the 2N system

[smerriman]

Joshua Donn, who was the GIB developer who would interact with the forums many years ago, said in 2018:

 

It has been a long time goal of mine to have a rule created that GIB always bids blackwood on the way instead of jumping to 6 or 7 of any suit.

Then he left and hasn't been back since :)

 

But in this auction, 4NT isn't Blackwood anyway. I think the problem here is that the bidding database is very poor when it comes to slam auctions. Which isn't a great surprise as most grands need to be bid based on counting tricks rather than points / rules - which its what its simulations are for.

 

But when it simulates, it plays out the rest of the auction using database rules only, without knowing that it'll be able to simulate to get to a better result later (recursive simulations are too time consuming). If it starts with 4♦ the database will probably tell it the auction will end up at 6♦ even when 7♦ is stone cold. So when 7♦ is making a lot of the time, it decides blasting to grand will get a better average than the database, with all of the making grands outweighing the ones where it goes down.

 

But that's just a guess; the old version of GIB is far weaker and North bids an immediate 6N over West's double of 2♣ :) Even if I hack the database a bit to get it to match yours, it still picks 4♦, so there have probably been a lot of changes here.