2C-2D-2N-3C followup Why does GIB react differently?
#1
Posted 2014-December-02, 13:29
KQ, xxxx, J, 9xxxxx
GIB bid 3NT. The meaning of a 3NT rebid by an opener is unclear to me, since you would want to leave room for responder to show a 4-5 or 5-4 hand if held. Perhaps it should show 2-2 in the majors, but that is not the description. The descriptions of 3D and 3NT, while not written identically, appear to amount to the same thing - 22-24 HCP and no 4 card or longer major. But yet, with the hand above, GIB bid 4C over 3NT.
So what IS the difference between 3D and 3NT?
#2
Posted 2014-December-02, 14:52
I think what posters find confusing is they expect GIB to make the exact same bid all the time with the exact hand and auction.
#3
Posted 2014-December-02, 15:59
OP made this point but I think it needs to be emphasised as 3N is functionally inferior unless it carried some special meaning which it appears not to.
Besides, the system notes (which apparently are out of date) do not give 3N as a possible response.
#4
Posted 2014-December-02, 18:01
mike777, on 2014-December-02, 14:52, said:
I think what posters find confusing is they expect GIB to make the exact same bid all the time with the exact hand and auction.
In placing a contract, GIB will sometimes do simulations and will make decisions based on a small sample size, but this is not supposed to happen earlier in auctions, and particularly not when GIB is responding to a conventional asking bid.
#5
Posted 2014-December-02, 18:15
whereas the explanation of 3N is "3-5♣; 3-5♦; 2-3♥; 2-3♠; 22-24 HCP..."
Ignoring the slight difference in minor suits, it would be my guess that the latter is not supposed to be part of the GIB bidding system, but it was put into the explanation grid simply so that GIB wouldn't freeze if his dumbass human partner made this bid.
#6
Posted 2014-December-03, 21:14
Bbradley62, on 2014-December-02, 18:01, said:
In placing a contract, GIB will sometimes do simulations and will make decisions based on a small sample size, but this is not supposed to happen earlier in auctions, and particularly not when GIB is responding to a conventional asking bid.
Why doesn't the robot's hand always match the description?
When humans play bridge, they don't just follow rote rules for bidding; they often use their judgement to find better bids, or fill in holes in their system. We would love it if we could program judgement into GIB, but that would be pretty advanced artificial intelligence. As with many game-playing computer programs (e.g. chess programs that routinely beat grandmasters), we substitute brute computational power for thinking. Many of GIB's rules allow it to perform simulations.
GIB starts by finding the matching bid in its bidding rules (we call this the "book bid"). If simulations are allowed, it then makes some adjustments to its hand (adding a card to each suit, adding/subtracting a few total points) and finds the book bids for those similar hands. Then it deals out cards to the other hands at the table consistent with the rest of the auction. For each hand and possible bid, it does 2 things:
1.Determine how the auction will probably continue if it makes that bid (to avoid exponential complexity, it only considers book bids for this continuation, not what would happen with subsequent simulations), and
2.Calculate the double-dummy result of the final contract determined in step 1.
It then selects the bid whose expected value is highest across all the hands. This takes into account the form of scoring; this is how we emulate rules of thumb like "bid games more aggressively when vulnerable at IMPs". The description that's displayed comes from the specifications of the bid that was chosen; this corresponds to the standard rule about disclosure in bridge: you must describe your agreements, not your actual hand
#7
Posted 2014-December-03, 21:53
I still think you're overstating the frequency with which GIB simulates during auctions, and will await clarification from staff/programmers. I don't think GIB will ever, for example, bid 3N over 3♣ as several humans did in the OP. Another example would be when GIB decides whether to super-accept a transfer; I think this is also decided by rules, not by simulation. It appears to me that these simulations are reserved for final placement of contracts.
#8
Posted 2014-December-03, 23:18
Bbradley62, on 2014-December-03, 21:53, said:
I still think you're overstating the frequency with which GIB simulates during auctions, and will await clarification from staff/programmers. I don't think GIB will ever, for example, bid 3N over 3♣ as several humans did in the OP. Another example would be when GIB decides whether to super-accept a transfer; I think this is also decided by rules, not by simulation. It appears to me that these simulations are reserved for final placement of contracts.
3nt would be a "final placement of contracts"
#9
Posted 2014-December-04, 03:08
mike777, on 2014-December-03, 23:18, said:
But a premature one, by the hand that is not in charge.
London UK
#11
Posted 2014-December-04, 15:09
mike777, on 2014-December-03, 21:14, said:
Hmmm, when my partner bids Stayman and I count the cards in my major suits and if I don't have 4+ cards in either major, I bid the appropriate level of diamonds. I don't use judgement to find a better bid because in response to a standard Stayman bid, there are only 3 expected responses. You can't go around making up responses to a conventional bid and expect partner to figure out your brilliancy.
#12
Posted 2014-December-04, 19:24
Again feel free to tell that to the machines.
My Bridge Encyclopedia indicates there seems to be more than one standard reply but your points are excellent.