xeno123, on 2017-September-05, 09:55, said:
1. How to improve the bidding? I was indeed worried about the Q♠ but couldn't figure out what to do about it after the 5NT reponse.
2. Why did the robot East not cover the J♠? Certainly gave me heartburn, but I figured I had to play East for the Q anyhow.
3. Why does covering the J turn out to be the only way to set the contract?
4. Why did the robot East discard the A♥? Worried about an end-play perhaps? And why the club discards?
5. I think my play was sub-optimal, although it worked here. Can someone else confirm what I think to be a slight improvement? (Incidentally nobody else in a field of 105 bid and made the spade grand slam - one other player bid and made 7 diamonds, with 6NT being a popular contract).
1. You don't know what North's void is, and you are missing
♠Q. Once you bid 4NT, you are in trouble. GIB plays Soloway jump shifts, so you showed an independent strong suit when you bid 4NT. Your systemic bid after the spade raise would be 3NT to show a fairly balanced hand with a lot of points.
GIB could have bid 4
♥ instead of raising spades to show spade support and a void and then would have to adjust it's bidding to not bid 5NT over 4NT since the void was already shown. You would then be able to make a trump queen asking bid. Probably too much to expect from GIB programming.
3. If GIB covers the jack, you need 1 entry to take another finesse, another entry to trump a diamond to reduce your trumps to the same length as East, and a third entry to execute the trump coup. You only have 2 entries.
4. A GIB surrender play? You are marked with the
♣A so it doesn't matter what GIB discards if you play the cards correctly. GIB frequently throws random cards when analysis shows that it doesn't matter.
edit add - 5. Playing
♠AK only picks up Q10 tight. Running the jack can pick up Q10 or (Q10x or Qxx depending on your 2nd trump play) (or Qx if East doesn't cover).
If RHO covers ♠J, then you need the ♣ finesse to work to give you 3 dummy-entries,
- to finesse ♠9
- to shorten your trumps with a ♦ ruff and
- to run dummy's ♦ to coup RHO's trumps.
RHO failing to cover ♠J means that you only need 2 entries to dummy -- which is lucky when RHO holds ♣Q.
After finessing ♠9 and cashing ♦AQ, declarer must guess who has ♣Q.
If LHO has ♣Q, then you should ruff a ♦, immediately, before RHO gets rid of too many ♣s. With no other information, I think this is the distribution for which declarer should play. Hence RHO GIB's discard of ♥A was precipitate surrender..
.
IMO, it's inferior to play RHO for ♣Q, as here. Although, you can still succeed with an unusual kind of front-wash squeeze:
When you guess that RHO has come down to a singleton ♣Q, then ruff a ♦ and return to dummy with ♣K. Later, when RHO ruffs, you can over-ruff, draw trumps, and re-enter dummy with ♣J to cash dummy's ♦s.