[uva72uva72]

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IMPS, ACBL robot individual

BBO's "GIB Bid Description" refers to what it calls a rule of thumb: "bid games more aggressively when vulnerable at IMPs" and 9 participants in a recent IMP robot individual implemented that rule of thumb. Expecting North to have some semblance ofthe described "10-14 total points," 9 Souths implemented BBO's rule of thumb and bid 5♣. Needless to say, dummy was a disappointment, as was the 12 IMP loss that resulted from being -800 and that effectively put them out of the competition.

If the BBO Bid Description is accurate, 4♣ should have been "the bid whose expected value is highest." From my vantage point as a technical ignoramus but a solidly average bridge player, 4♣ looks like matchpoint thinking, betting that partner will either make 4♣ (unlikely) or go down exactly 1 undoubled against the opponents likely +140. It also looks like North is taking credit for South's assumed ♠ shortage. At IMPs, this kind of risk taking makes no sense, especially since it ignores 2 additional risks - that partner will raise to 5♣, which rates to go down at least 2, perhaps doubled; or that the opponents will compete to 4♠, which looks cold to me. Ignoring the small stuff (potential gains and losses of 1 or 2 IMPs, the most likely results and no motivation for bidding), it looks to me like the best case scenario for a human North bidding 4♣ would be an outside chance of gaining 5 IMPs (+130/+ 140), against a small risk losing 8 IMPS (-500/+140) and an outside chance of losing 12 IMPs (-800/+170). No human would run an outside risk of losing 12 IMPs or even a small risk of losing 8 IMPs in pursuit of an outside chance of gaining 5.

I recognize that the analysis is different for robots, since if 1 bids 4♣ they all bid 4♣. Since South (who is limited by the failure to double or bid 4♣ directly over 2♠) cannot conceivably make 5♣ opposite North's mess, robot A's bid of 4♣ can only gain if robot A's partner passes while robot B's (and/or robot C's) bids 5♣. That makes North a croupier at a roulette table, not a bridge partner.

[Bbradley62]

In addition to agreeing that 4♣ is bad, I continue to be confused by GIB's implementation/explanation of The Law -- why does West think his side has 9 trumps?