[wbartley]

https://tinyurl.com/y74e2qfg

This is the sort of thing that makes me want to stop playing with robots. Now, if only there were some humans who could follow suit.

[pescetom]

I spend no time playing with GIB, but I do note you bid 2NT described as 19-21 when holding 23. It's not a bid I would have risked even with a random human.

[smerriman]

Agreed, as North I would have bid 3♦ rather than pass 2NT but I'm not sure what that has to do with finding an 8 card heart fit. South should bid 2♠ over 2♦ surely?

[pilowsky]

Unlike some other players on the Forum, I actually enjoy playing with the robots.
They come with a reasonable instruction manual that they never deviate from.
Robot declarer play is considered (by the manufacturer) to be 'Expert level'.
Bidding is a different problem.

According to the Author of GIB:
"All of these techniques are used, and all of them are useful. Gib's bidding is substantially better than that of earlier programs, but not yet of expert caliber". [1]

Ginsberg's statement fits with (my) human experience. It is easier to develop expertise at being a Declarer than at being a Defender. Becoming good at bidding may be a lifetimes work.
The same is true in other games (and life in general!).
Playing chess requires a deep knowledge of the openings to avoid falling into obvious traps. You cannot avoid this component; you have to learn a repertoire of openings (just like bidding). The middle game is a different story. Here it would help if you had a deep understanding of strategy and tactics along with the ability to bamboozle your opponent to reach an optimal ending.
Finally, many 'set-piece' endings must be conquered.
Almost anyone can checkmate with a queen and king vs king. Try doing it with two knights in less than 50 moves.

Ginsberg rates his brainchild as an expert level Declarer but less good at defending and bidding. I would agree.

Looking at your specific example where EW has no makeable contracts (https://dds.bridgewe...78.44026004.pbn), but NS can make either 5♦ or 5♥, it looks like the West robot with 11 losers decided to keep his nose clean: notwithstanding the 9 card fit.
Points may not be everything, but they do help.

I gave Gib this hand, and it bid 'pass' as West. This is what the NS robots did.
5♦ makeable, but 4♥ is better.
As a newbie, I find the problem of trying to find an 8-card fit with a 4/4 split as an overcaller playing 5 card majors as problematic.
Sometimes as an overcaller, I'll bid my 4-card major and expect to take my chances in a 4/3 fit if it turns out that way.
On the teaching table, if I bid the hand the way you describe, East bids as follows:

---

When I let GIB play this sequence out, the score is 3♠-2 +100 to NS (300 if doubled).
Finally, I tried bidding 1NT as the opener to see if East would evaluate its hand with 5/4 in spades and a minor as worthy of bidding 2♠ Cappelletti. It passed. NS then went for -200 in 7NT (obviously).
Which just goes to strengthen the point that Gib - like most humans - is better at Declaring than Defending since it should go -5, not -4.

To the extent that computers 'think', It looks to me like EW thinks it is going nowhere in this auction and wisely steps aside, hoping that NS will reach a sub-optimal contract.

What did you want GIB to do, what did others do, and what was your score on this hand?

[1] Ginsberg ML (2001) https://www.jair.org...iew/10279/24508

[wbartley]

If my hand is indeed limited to 21 then that's all the more reason for GIB to bid 3♦. If it's going to pass 2NT, it should at least have the courtesy to bid 3! I challenge you to produce a 19-21 point hand matching my bidding on this auction that makes 2N opposite the given hand but doesn't make 3N. Passing 2N with essentially a zero count and 6-4 in the red suits is ridiculous.

[smerriman]

GIB is programmed that bidding a second time shows 4-5 total points. Yes, not a great rule, but I'm still not sure how you were intending to find 4♥.

[pescetom]

wbartley, on 2021-February-18, 20:31, said:

I challenge you to produce a 19-21 point hand matching my bidding on this auction that makes 2N opposite the given hand but doesn't make 3N.

1.
T                   A K J 5 4           Q 9 3               8 7 6 2 
9 8 5 2             J                   A Q T 7             K 6 4 3 
J T 8 6 4 3         K 7                 A 5 2               Q 9 
6 3                 J T 9 8 7           A K 4               Q 5 2 

   2.
T                   Q 6 4 3 2           A K J               9 8 7 5 
9 8 5 2             J 4 3               A K Q 7             T 6 
J T 8 6 4 3         A K                 Q 5                 9 7 2 
6 3                 A 7 4               J T 9 2             K Q 8 5 

   3.
T                   K J 9 6 5           Q 7 2               A 8 4 3 
9 8 5 2             Q                   A J 6 3             K T 7 4 
J T 8 6 4 3         Q 5                 A K 9               7 2 
6 3                 K J T 9 2           A Q 5               8 7 4 

   4.
T                   Q 9 8 4 3           A K J               7 6 5 2 
9 8 5 2             Q T 4               A K 6 3             J 7 
J T 8 6 4 3         K 2                 A Q                 9 7 5 
6 3                 K Q 7               9 5 4 2             A J T 8 

   5.
T                   K Q 7 3 2           A J 8 4             9 6 5 
9 8 5 2             K                   Q J 6 4             A T 7 3 
J T 8 6 4 3         7 2                 A K 9               Q 5 
6 3                 K Q J 9 2           A 5                 T 8 7 4 

   6.
T                   A Q 9 8 7           6 4 2               K J 5 3 
9 8 5 2             T 7                 A Q 6 4             K J 3 
J T 8 6 4 3         5 2                 A K Q 7             9 
6 3                 K Q 9 4             A 5                 J T 8 7 2 

   7.
T                   Q J 9 6 3           A K 2               8 7 5 4 
9 8 5 2             K T 3               A Q 7 4             J 6 
J T 8 6 4 3         K 5                 A 7 2               Q 9 
6 3                 K J 9               Q T 5               A 8 7 4 2 

   8.
T                   A 8 4 3 2           K 7 6               Q J 9 5 
9 8 5 2             7 3                 A K T 6             Q J 4 
J T 8 6 4 3         Q 5                 A 7 2               K 9 
6 3                 K Q T 9             A J 4               8 7 5 2 

   9.
T                   Q 9 7 6 3 2         A J 8               K 5 4 
9 8 5 2             6                   A K T 4             Q J 7 3 
J T 8 6 4 3         K                   A Q 9 2             7 5 
6 3                 A Q 9 8 5           J T                 K 7 4 2 

  10.
T                   K Q J 4 3           A 5 2               9 8 7 6 
9 8 5 2             J 4                 A K 7 3             Q T 6 
J T 8 6 4 3         Q 9                 A 7 5               K 2 
6 3                 Q J 8 7             A 9 2               K T 5 4 

Generated 83855 hands
Produced 10 hands
Initial random seed 1613843443
Time needed    3.716 sec

[pescetom]

wbartley, on 2021-February-18, 20:31, said:

If my hand is indeed limited to 21 then that's all the more reason for GIB to bid 3♦. If it's going to pass 2NT, it should at least have the courtesy to bid 3! I challenge you to produce a 19-21 point hand matching my bidding on this auction that makes 2N opposite the given hand but doesn't make 3N. Passing 2N with essentially a zero count and 6-4 in the red suits is ridiculous.

The rough and ready simulation below says that with 19-21 HCP as promised you make 2NT 13% and 3NT 4%.
So 2 out of 3 hands that make 2NT will not make 3NT, I listed 10 of them above.

Having said that, 3♦ makes 80%.
4♥ in 4-4 makes 24% (even with 23 HCP rises only to 52%).

#what can NS make with this hand after 1S opening by E and takeout then 2NT by South?

predeal north ST, H9852, DJT8643, C63
S2NTcrit = (hearts(south)==4 and spades(south)>=3 and diamonds(south)>=2 and clubs(south)>=2 and hcp(south)>=19 and hcp(south)<=21)
E1Sopen = (spades(east)>=5 and hcp(east)>=11)
produce 1000
make2N = (tricks(south,notrumps) >= 8)
make3N = (tricks(south,notrumps) >= 9)
make3D = (tricks(north,diamonds) >= 9)
make4H = (tricks(north,hearts) >= 10)
action frequency "of making 2NT" (make2N,0,1), frequency "of making 3NT" (make3N,0,1), frequency "of making 3D" (make3D,0,1), frequency "of making 4H" (make4H,0,1)
condition S2NTcrit and E1Sopen