GIB System Notes

GIB System Notes


We have created a standard convention card for GIB. Click here to see GIB's convention card.

In general, the GIB robots on BBO use the 2/1 system described below. You can click on any of GIB's bids for an explanation, and pause your mouse over a bid you plan on making to see how it will understand it.

Click here for help understanding these explanations.

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Overview

2/1 Game Force with 5 card majors, strong NT, strong (17+) jump shift, weak 2 bids and a strong artificial 2♣.

HCP vs Total Points

Gib uses both old fashioned HCP (A=4, K=3, Q=2, J=1)) and “Total points” (HCP+3 for void, 2 for singleton, 1 for doubleton, but short suits containing an honor are reduced by 1 point). It will usually force to game if it thinks it has 25 Total Points between the two hands.




How GIB Defends

It's difficult to describe precisely how GIB defends. It doesn't use rules and guidelines, like humans often do. It simulates hands based on the auction, using double dummy analysis to determine the average result of each defensive play, and chooses the one with the best average. Sometimes this simulation comes up with the same choice that a human would make (there's a good reason for some of the guidelines -- they actually work well), but not always (some of our rules of thumb have become popular simply because they're easy to remember and "good enough"). When it has a choice of equivalent cards, it will choose based on leading and signalling conventions.

GIB doesn't interpret your signals or make many inferences from the play, it uses simulations based on the auction. However, it's usually able to figure out that when you lead an honor, it's part of a sequence.

GIB usually leads passively against NT (read the book Winning Notrump Leads to understand why). Don't assume it's leading its longest suit. When you lead, it doesn't assume you're leading your best suit, which is why it doesn't always return the suit like a human would.

In suit contracts, GIB's opening lead is frequently a side singleton or doubleton, to try to get a ruff. When it leads a suit bid by the opponents, this is almost always the reason. Read the book Winning Suit Contract Leads for insight on the way GIB leads against suits.

If it leads an honor that's part of a sequence, it uses standard honor leads (K from AKx, A from AK doubleton). If it leads from a long suit, it leads 4th best (but see above: it doesn't always lead its long suit). When leading from 3 small, it leads top of nothing against NT, low against a suit contract.

It doesn't use any signals when making discards, it just tries to make safe discards. In a suit contract it will frequently discard from a short suit while it has trumps left. Otherwise, it tends to discard from a long suit that's safe to shorten.

When it's following to partner's opening lead, it will usually give an attitude signal:


When it's trying to win the trick in third hand, it will play the lowest of equals. Otherwise, when following suit it usually gives standard count signals (high = even); an exception is when it's forced to play equivalent cards in a doubleton, it will randomize them because of "restricted choice".



Bidding

Basic Approach

Opening bids

1♣

could be 3 if 4333,3433 or 4423. 2♣ response is forcing, inverted

1

usually 4 unless 4432. Opens 1 with 4-4 in the minors. 2 response is forcing, inverted. 2♣ response is forcing for one round, but not game force.

1 1♠

normally show 5 in all seats. Opens 1♠ with 5-5 in spades and clubs. 1M-2M direct raise shows 7-10 points. 1N response is forcing. Jacoby 2NT. Splinters.

Two-way game tries.

1NT

balanced 15-17 HCP, may have a 5-card major (GIB treats 17 with 5-card major as 18). Followups

2♣

strong, artificial. 22+ HCP

2 2 2♠

weak 2 bid. Disciplined, with honors in the suit

2NT

balanced 20-21 HCP, may have a 5-card major.  Followups



Responses and Rebids

Competitive Auctions

Other conventions and treatments

Notes

Conventions that GIB does not play



Two-way Game Tries

After a single raise of a major suit, GIB plays two-way game tries.




Roman Keycard Blackwood (RKCB)


RKCB is a 4NT bid that, unlike regular Blackwood, asks for "keycards" instead of Aces. There are always 5 keycards - the 4 Aces plus the King of the agreed trump suit. If no trump suit has been clearly agreed, the King of the most recently bid suit is typically counted as the 5th keycard.

Responses to 4NT RKCB 0314:


After the 5♣ and 5 responses, the 4NT bidder can bid the next step that is not a signoff in order to ask for the Queen of the agreed suit. Then:

     

A subsequent 5NT bid by the 4NT bidder (regardless of whether or not an ask for the Queen of the agreed suit has taken place) asks for specific Kings. The 5NT bid promises that all of the 5 keycards and the Queen of the agreed suit are accounted for. Then:

     

DOPI after interferences:






After a 1N opening bid


If the opponents overcall 2♣ (Cappelletti any 1-suited hand), Double is Stayman and all other bids as below. If the opponents double, all systems are on; Redouble is used to run out to a minor (opener should bid 2♣, responder passes or corrects to 2). After any other interference, Lebensohl is used.



After a 2N opening bid



Soloway Jump Shifts

GIB plays Soloway Strong Jump Shifts by an unpassed hand in uncontested auctions. A jump shift shows one of the following types of hands:

  1. Strong rebiddable suit, 17+ total points, 4+ controls (A=2, K=1), no side 4-card suit
  2. Solid suit, 17+ total points, 4+ controls, may have a side 4-card suit
  3. Rebiddable suit, 18+ HCP, 4+ controls, 5332 or 6322 shape.
  4. Rebiddable suit, 17+ total points, 4+ controls, 4-card support for opener's suit


Opener can rebid his suit to show 6+, raise responder or bid RKC Blackwood with 3+ support, bid a side suit to deny support and show least KQ in the  suit, or bid NT at the cheapest level to show any other hand.


Jump shifter shows which type of hand it had with its next bid:



Reverse Drury

GIB plays one-way Reverse Drury when partner opens a Major in 3rd or 4th seat. A 2♣ response shows at least 3-card support and invitational values (11-12 total points). This is not used if there is any interference; Jordan/Truscott 2NT is still used to show a limit raise over a double, a cue bid is used after an overcall, and 2♣ is natural (weak after a double, one-round force after an overcall).

Opener's rebids are as follows: