[mgoetze]

 barmar, on 2015-March-04, 10:40, said:

I agree that it doesn't take good advantage of knowing which doubleton opener holds. But I've never seen it wrong-side the contract, since it always just re-transfers.

Well there is usually one answer where no retransfer is available e.g. 2NT-3♦-4♦.

[Siegmund]

I approach the tournaments primarily as declarer play practice, with a tiny bit of hand evaluation on the side. As such I prefer it when normal people have normal auctions. When I open 1C and rebid 1NT on my bad 14 count, it annoys me to get random noise added by the people who deliberately lied to the robot. Annoys me in a way that people playing a different system wouldn't.

I do find I bid differently with my 11s and 12s when I know partner is weaker. But I have yet to see any systematic advantage for the people who open 1NT on everything under the sun. Eventually it causes them to miss their 26-point 3NTs and get to their 23-point 3NTs, and it's hard to turn a profit doing that.

There are plenty of interesting bidding decisions on the competitive hands or on the "is it worth a slam invite?" problems.

[barmar]

 mgoetze, on 2015-March-04, 17:57, said:

Well there is usually one answer where no retransfer is available e.g. 2NT-3♦-4♦.

Jumping in the suit that the transfer goes to shows a doubleton in the suit of the transfer. So to show a doubleton ♦, bid 4♥.

[Bbradley62]

 Bbradley62, on 2015-March-02, 12:16, said:

 ArtK78, on 2015-March-02, 11:16, said:

GIB loves to lead from a short holding. This is even true against NT contracts (some might even say it is especially true against NT contracts). So, don't assume that GIB is leading from length.

This statement surprised me, so I tried to verify it from my recent hands. I found it to be true in only 5 of the first 20 NT contracts I checked (GIB led his best suit the other 15 times), then I stopped looking. My strictly-from-memory impression is that GIB does lead a lot of doubletons against suit contracts.

Then, today I got these two...

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[barmar]

GIB's opening leads are based almost entirely on simulations based on the auction. The only rules it uses are after it decides to lead from a particular holding, it uses a table of lead agreements to know which of equivalent cards to lead (e.g. A versus K from AKx).

As I've mentioned many times, if you want to understand this process, read the Bird and Anthias books on opening leads. Their analyses were also based on computer simulations. However, because GIB is under time constraints that B&A didn't have, it can't simulate thousands of hands like they did, it only does a few dozen, so it's more likely to make mistakes due to sampling error.