[lamford]

---

IMPs. Strong Event.
A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There shallow draughts intoxicate the brain,
And drinking largely sobers us again. - Pope

Don't bother with Suitplay or the Encyclopedia of Card Combinations; they are both wrong.

You win the jack of clubs lead in South and lead the queen of diamonds covered, and East plays the five. Over to you.

[mikeh]

It’s as close to a pure guess as you’re ever going to see

West has to cover with K stiff or K10 tight

He can never cover with Kxx

Covering with Kx is more ‘normal’ but not a good idea unless trying to pretend to have K10

East’s 5, not being the 4, may suggest that west has the 4 but strong defenders randomize spots routinely in these situations

Also, less than strong opponents might break tempo before covering wth Kx

So these very weak inferences have me hooking on the way back since stiff King and K10 tight offset and the very slight remaining edges favour west having erred

[Douglas43]

Here's a Palooka view to start you off, looking at the diamonds in isolation:
(1) ignoring situations where you are never or always making four tricks in the suit and
(2) assuming West defends the position perfectly (covering the second honour with Kx)

There are two stand-out positions where West must cover the first honour; West has K10 doubleton when you must play for the drop, or West has singleton King, when you must finesse.

The two chances in (2) cancel each other out. Finessing works half the time. So win it and finesse the 8.

[Mikeh posted while I was writing. At least I'm in good company]

[nullve]

lamford, on 2021-May-04, 05:59, said:

You win the jack of clubs lead in South and lead the queen of diamonds

Why don't I make a discovery play instead, by losing a club trick early?

[lamford]

nullve, on 2021-May-04, 11:28, said:

Why don't I make a discovery play instead, by losing a club trick early?

If you do they will both follow to the second club. You still have to play the diamonds for no loser. I don't think you gain anything by ducking a club.

[nullve]

lamford, on 2021-May-04, 12:12, said:

I don't think you gain anything by ducking a club.

---

---

[Cyberyeti]

lamford, on 2021-May-04, 12:12, said:

If you do they will both follow to the second club. You still have to play the diamonds for no loser. I don't think you gain anything by ducking a club.

Well not unless you discover he had 525 in the non diamond suits when cashing the side winners it's then 100% as long as you are in dummy with an entry to dummy left

[akwoo]

I'm not so sure about West never covering with Kxx.

Haven't you ever been stolen from by South having

AKxx
KQxx
Q
Axxx

in this situation?

(Okay, probably South wouldn't have opened 2N with that, but...)

[mikeh]

akwoo, on 2021-May-04, 14:56, said:

I'm not so sure about West never covering with Kxx.

Haven't you ever been stolen from by South having

AKxx
KQxx
Q
Axxx

in this situation?

No

[lamford]

Cyberyeti, on 2021-May-04, 12:40, said:

Well not unless you discover he had 525 in the non diamond suits when cashing the side winners it's then 100% as long as you are in dummy with an entry to dummy left

As I said, on the hand you will not gain anything by ducking a club, as they both have three. You will still have to guess the diamonds. If you lead the queen, West will cover and nothing will happen when you play one back towards your hand. And neither opponent has a doubleton in either major.

[nige1]

Lamford 'IMPs. Strong Event.A little learning is a dangerous thing;
Drink deep, or taste not the Pierian spring:
There shallow draughts intoxicate the brain,
And drinking largely sobers us again. - Pope
Don't bother with Suitplay or the Encyclopedia of Card Combinations; they are both wrong.
You win the jack of clubs lead in South and lead the queen of diamonds covered, and East plays the five. Over to you.
+++++++++++++++++++++
IMO, West should always cover the ♦Q when he holds ♦Kx doubleton (in case declarer's holding is weaker e.g. ♦QJ8x). Hence, after winning ♦A, declarer should finesse ♦9 -- paying off to ♦KT doubleton with West.
Were North declarer, different considerations might apply.
Nullve's suggestion of ducking a ♣, before deciding how to continue, helps in some layouts and can hardly cost.

---

[nullve]

lamford, on 2021-May-04, 16:20, said:

As I said, on the hand you will not gain anything by ducking a club, as they both have three.

---

---

[nullve]

lamford, on 2021-May-04, 05:59, said:

You win the jack of clubs lead in South and lead the queen of diamonds

nullve, on 2021-May-04, 11:28, said:

Why don't I make a discovery play instead, by losing a club trick early?

Correction: Leading the ♦Q at trick 2 cannot hurt, and will actually put the maximum pressure on LHO. (The discovery play can wait.)

[lamford]

nullve, on 2021-May-05, 04:14, said:

Correction: Leading the ♦Q at trick 2 cannot hurt, and will actually put the maximum pressure on LHO. (The discovery play can wait.)

I agree. All discovery plays will not learn anything on the actual hand, as nobody has a doubleton or shorter, and you are forced to fall back on the diamond guess.

I think that correct game theory is to lead the queen and if it is covered, as mikeh says, to finesse the nine on the way back. It is only correct for West to duck from Kx if he sees the nine AND knows that the closed hand has four diamonds. Where suitplay and the Encyclopedia go wrong is that they assume that the defence can see all the pips and that they know that it is an 8-card fit. Rarely the case.