[nige1]

West led ♣A against South's 6♠

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[pilowsky]

Nige1 "got lucky in Glasgow".
I looked up how GIB decides on leads in the system notes.
It said "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.<br style="">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 low against both suit and NT contracts."

This information was so useful that a month ago I went out and bought these two books.
It turns out that to make sense of GIB leads you have to memorise 2 volumes of books about simulations that give multiple answers in IMPs and matchpoints - it's taking a bit of time .

Mr Bird and Mr Anthias report that "when leading against undisciplined suit slams..." Help me out here, is this slam undisciplined? mine are just silly, but there you go, it USED to be thought (50 years ago - around the time of the Bridge teachers at the coffee shop where I learned duplicate for the first time) that leading an Ace was bad. "Don't bang down your Aces boy!"
After doing thousands and thousands and thousands of simulations, the following advice popped up in the first Hand (Ch14). You're getting it second hand so it may be wrong...

Lead ___Matchpoints___ IMPs

♠3______14.3%___ ___0.72

♥9 ____13.0% ______0.70

♦A ___ _17.6% ______1.11

♣2 ___ __14.3% ______0.72



"The A is best at IMPs and best by a landslide margin at match-points. The chance of partner holding a singleton or void diamond is only 2.6%. On auctions that have not confirmed a diamond control by cue-bidding (our current assumption), there is a 24.7% chance that partner will hold the K You may then have two diamond tricks to cash. Note that South will hold a diamond control by shortage 28.5% of the time; North will hold such a control 22.7% of the time.
South will hold the OK with frequency 36.1%, so leading the A will often set up this card. Nevertheless, it is best in the long run to lead the ace. What sort of deal lies behind an 'undisciplined slam auction"? Let's pick one from the simulation, so that we have some idea."
Bird and Anthias "Winning suit contract leads" 2018. ISBN 978-1-55494-769-0

Their general conclusion seemed to reinforce the point.
I hope they produce more of these excellent books the advice is cogently presented and makes a lot of sense. Of course, even if there is a 90% chance of rain, the people living in Bourke will never get any.
In my system, I always seem to cunningly choose the only lead that will allow the contract to make over-tricks. I think the best way to choose a lead is to ask me first - if I'm available.

[Tramticket]

Nice trump coup to recover from the 5-0 break Nigel. Yes, the cards sat where you needed them to be, but still rather elegant.

[johnu]

GIB is demanding a recount and if the contract is not corrected to down 1 then GIB will unilaterally change the score.

[nige1]

 johnu, on 2021-January-06, 02:50, said:

GIB is demanding a recount and if the contract is not corrected to down 1 then GIB will unilaterally change the score.

Initially, I thought South was on tram-lines and that East might defeat the contract, by covering dummy's hearts. It surprized me that, according to GIB, at double-dummy, declarer has a choice of plays make on a ♣ lead.