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How GIB responds with both Majors 5422 as responder

#1 User is offline   pilowsky 

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Posted 2021-May-28, 17:57


A.
I was dealt this hand on the teaching table a moment ago.
Thinking that my bidding had caused a problem I gave it to GIB to bid as South.



B.
GIB bid it the same way.


In both cases, the rebid of 2 promises 4 which GIB does not have.
After bidding (my majors up the line) 2, GIB calls this a "game try suit" with only 3.
Is this because I am supposed to bid the 5 card suit first?


C.
Here's what happens if I reduce South's holding by one spade and give it 3's
Now South ignores the 4 card spade suit (presumably because it's convinced it already has an 8-card major fit) and bids 3 "Game try suit -- 3+; 4+ ; 10+ HCP; 11+ total points; forcing to 3.


The GIB system notes are an excellent resource for many aspects of GIB behaviour.
This is not one of them.
Welsh Clog dancing makes more sense than this - https://bit.ly/WelshClogDance
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#2 User is offline   Stephen Tu 

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Posted 2021-May-28, 19:09

It is extremely strange for anyone, including GIB to respond 1H as South. I just tried the same hand at a bidding table, the robot responds 1S as expected every time when left to its own devices, so I'm curious how you managed to get a robot to respond 1H, unless you forced the 1H bid first, before letting the robot bid the rest?

Generally, for standard natural systems, the rules for responding with both majors to a minor are:
1. If one major is longer, bid it first. (So here bid spades).

2. If both majors are the same length, and only 4 cards long, bid hearts first. This allows you to find a fit in either major, as opener will raise hearts with hearts, and bid spades with spades. (This gets a bit more complicated in systems where you allow opener to bypass bidding 1S to rebid 1nt or 2nt. Then you need gadgets/different sequences to find the spade fit and distinguish 4s 5+H from 4s 4H, and in some cases responder won't be strong enough to find the spade fit). If partner doesn't bid spades (except when partner rebids NT if you allow hidden spades there; for GIB 1nt denies spades, but 2nt can still have spades), and doesn't raise hearts, you just proceed knowing you don't have a major fit.

3. If both majors are the same length, and at least 5 cards long, bid spades first. This is because you expect in most cases (when partner doesn't raise, and if you are strong enough, which depends on what partner rebids) to bid hearts, then maybe hearts again, which will then show 5-5. This sequence allows preference back to spades without increasing the level. If you bid hearts then spades, partner expects longer hearts, and also a GF hand. The exact details depend on what to bid on 2nd round depend on how strong you are and what partner rebids, and partnership agreements. In some cases you might bid 1S then jump to 3H, if partner bids 1nt you might bid some artificial checkback gadget (new minor forcing, or xynt, or 2-way checkback etc.) if invitational+, because 1m-1s-1nt-2h is a non-forcing call for almost all systems.

As for North raising hearts on 3, it is common to allow raises on 3 with an outside singleton, as that is considered more palatable than rebidding 1nt on an outside stiff, or rebidding a poor 5 cd minor (here rebidding 2c wouldn't be ridiculous). Many times partner has 5 cds and you are fine, sometimes better off because partner would not have been strong enough to explore for the 5-3 fit if the rebid had been something else, and sometimes the 4-3 fit plays well.

But GIBs followup sequences after a 3 cd raise are often pretty questionable/buggy, if south tries 2s North should maybe suggest NT; and with the 4432 hand you presented last perhaps 2nt is a better game try than 3c.
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#3 User is offline   pilowsky 

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Posted 2021-May-28, 19:43

View PostStephen Tu, on 2021-May-28, 19:09, said:

It is extremely strange for anyone, including GIB to respond 1H as South. I just tried the same hand at a bidding table, the robot responds 1S as expected every time when left to its own devices, so I'm curious how you managed to get a robot to respond 1H, unless you forced the 1H bid first, before letting the robot bid the rest?

Generally, for standard natural systems, the rules for responding with both majors to a minor are:
1. If one major is longer, bid it first. (So here bid spades).

2. If both majors are the same length, and only 4 cards long, bid hearts first. This allows you to find a fit in either major, as opener will raise hearts with hearts, and bid spades with spades. (This gets a bit more complicated in systems where you allow opener to bypass bidding 1S to rebid 1nt or 2nt. Then you need gadgets/different sequences to find the spade fit and distinguish 4s 5+H from 4s 4H, and in some cases responder won't be strong enough to find the spade fit). If partner doesn't bid spades (except when partner rebids NT if you allow hidden spades there; for GIB 1nt denies spades, but 2nt can still have spades), and doesn't raise hearts, you just proceed knowing you don't have a major fit.

3. If both majors are the same length, and at least 5 cards long, bid spades first. This is because you expect in most cases (when partner doesn't raise, and if you are strong enough, which depends on what partner rebids) to bid hearts, then maybe hearts again, which will then show 5-5. This sequence allows preference back to spades without increasing the level. If you bid hearts then spades, partner expects longer hearts, and also a GF hand. The exact details depend on what to bid on 2nd round depend on how strong you are and what partner rebids, and partnership agreements. In some cases you might bid 1S then jump to 3H, if partner bids 1nt you might bid some artificial checkback gadget (new minor forcing, or xynt, or 2-way checkback etc.) if invitational+, because 1m-1s-1nt-2h is a non-forcing call for almost all systems.

As for North raising hearts on 3, it is common to allow raises on 3 with an outside singleton, as that is considered more palatable than rebidding 1nt on an outside stiff, or rebidding a poor 5 cd minor (here rebidding 2c wouldn't be ridiculous). Many times partner has 5 cds and you are fine, sometimes better off because partner would not have been strong enough to explore for the 5-3 fit if the rebid had been something else, and sometimes the 4-3 fit plays well.

But GIBs followup sequences after a 3 cd raise are often pretty questionable/buggy, if south tries 2s North should maybe suggest NT; and with the 4432 hand you presented last perhaps 2nt is a better game try than 3c.




Yes, you are correct (I just added A B C labels) - in Hand B I forced the 2H bid and then put a robot in South.
The result is different (3NT-1) if the robots bid and play the original hand.
Interestingly, the 2 bid is alerted at 3+, not 4.


In Hand C., the deal was loaded to the teaching table (in Prime if that makes any difference) with robots at all four seats.
I just tried it again same bidding same play same result.
My link
They force to game and North chooses a (possible) 4/3 fit in Hearts.

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