Stealth Revision?

[iandayre]

This isn't the first time recently I have suspected that there have been unannounced changes to GIB. If this is one, it's very positive.

 

http://tinyurl.com/kz4nhe6

 

With only 9 HCP GIB did very well to move to the near-cold slam with no wastage opposite the splinter.

 

The hand also demonstrates that while Axx is good opposite a splinter, xxx is even better. The slam is far less good with responder's minor suits reversed.

[1eyedjack]

I can't get too enthusiastic without seeing how GIB would have bid it with North's minors reversed. For all I know it might have bid the same.

[iandayre]

It's hardly awful even if that is the case. A small Club beats it if opening leader has neither missing honor, or the A only, and the latter lead is unlikely to be found. You have excellent chances on any other lead, and with friendly breaks you will take all the tricks.

[barmar]

There are no "stealth revisions", we announce every upgrade to GIB. We upgraded GIB last night, about 13 hours after you posted this example. And this isn't even new behavior; I just tested it with version 28 (3 revisions ago), it also bid 4NT.

 

This decision comes from simulations. With the minors as they are, it bid 4NT in all 10 simulations I tried. Swapping the minors, it bid 4NT in 8 of them. So it probably would have bid 4NT at the table.

 

Then I tested with the new version we installed last night. With ♦543 it still bid 4NT 100% of the time. With the minors swapped, it bid 4NT 5 times, 4♠ 4 times, and 5♦ once.

[iandayre]

Thank you Barmar. I will take your statistics at face value. But I must say, you can ask any regular GIB player, and they will tell you that GIB typically does not handle splinters well. It often signs off with perfect fits and bids again with wasted cards in the splinter suit.