[eagles123]

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lead is the 4 of ♦

finesse or not?

Thanks,

Eagles

[PhantomSac]

What are their leads?

If they lead fourth and lead low from 3 small for instance they have KT54(x) or K954(x) a lot, unless they have 43 or 42 doubleton or a stiff. If they lead mud or high from 3 small it's different, and if they lead 3rd and 5th its a lot different obv so knowing their leads would be a good start.

[eagles123]

4th best/MUD

[SteveMoe]

Rise Ace, draw trumps and pitch a losing ♠ on the 3rd round of clubs. You didn't get a ♠ lead so guarantee 5 and win the match on the next board.

[billw55]

The non-spade lead presents an opportunity. We are now cold for 5 if we choose.

If spades are led at other tables, they will need the diamond hook to make 5. So if we rise with the ♦A and the hook is working, we break even with them; if not, we gain. If we take the hook at trick one, the situation is reversed. We gain when the hook works (making 6 against their 5), and break even when it doesn't.

However there may be good reasons that a spade was not led. Most likely is that west holds the ace but not the king, in which case few tables will lead a spade. So the diamond lead may actually be common. Against that, a few tables may open NT and play 4♥ from the other direction, in which case a spade becomes more likely.

After all that, I still cannot find a compelling reason to hook or not. However, there is a small chance that the lead is a singleton. I need some reason to decide so I will use that, unlikely as it is. ♦A and draw trump.

[ggwhiz]

I'm greedy at mp's and will hook it and make 6? It's not a stiff unless rho passed 1♣ on these colours with 6 quality diamonds and with a bit of shape a lot of hands with an expected spade honor or two plus the diamond king would have overcalled too so I think the lead is 4th from longest and strongest and take the risk.

It would be nice to have a small read on the opponents ie. 1st 2 hands against a pair in a speedball last night my lho led from 3 small with KTxx in 2 other unbid suits back to back.

[whereagles]

Ace, on "restricted choice" principles.

Reasoning: spade or diamond is the canonical lead. Since in this auction odds are clubs are like xxx or Jxxx suit, there is no need for an aggressive Hxx underlead. Hence, the fact that LHO selected a diamond makes it more likely he xxx in the suit, as with ♠Hxx ♦Hxx he might have chosen a spade instead.


Of course, this is all unlucky expert stuff. In practice you play the ace because 11 tricks at matchpoints should be a AVG+ score

[Vampyr]

billw55, on 2015-January-19, 08:27, said:

Against that, a few tables may open NT and play 4♥ from the other side

I think that this is pretty unlikely, since virtually no one opens any number of notrumps with 18 points. But the declarer may change for pairs playing transfer responses to 1♣.

Also maybe for pairs playing Mexican 2♦; I don't know what the responses are. And maybe Multi, if they play that the South hand qualifies for a 2♠ response but again, i don't know what hand types usually qualify.

[Wackojack]

If you had nothing to lose by taking the finesse then take it. Here if you take the finesse you make 12 tricks if it works and 10 tricks if it does not. If you rise with the ace you make 11 tricks regardless and beat all the tables where a spade was led. So you need to be pretty certain that LHO has the K. Assuming 4th highest then the combinations of cards with the King are K1094, K10943, K10942. Whereas without the K it could be 943,942,43,42, 4 plus if the 10 is not counted as an honour 1043,1042.

So rise with the ace.

[Fluffy]

In my country nobody underleads kings for some reason so this is a no brainer.

[mikeh]

Fluffy, on 2015-January-20, 16:18, said:

In my country nobody underleads kings for some reason so this is a no brainer.

I know players over here (all bad) who also seem to think that underleading a K is terrible. I think some of them think it better to underlead an Ace!

If I were the leader, the odds are 98% that the hook will work

[BillPatch]

Let's start by assuming we only know about the ♦ suit. Assuming standard leads, mud, and 2nd best from 4 cards W possible diamonds holdings are
kt5432, k95432, kt543, kt542, k9543, k9542, kt54, k954, kt4, k94, k54 with k onside and
9432, t54, 943, 942, 543, 542, 43, 42 and 4 with k offside.
3 6/1 splits 2 on 1 off * 7%/14
6 5/2 splits 4 on 2 off * 17%/56
11 4/3 splits 5 on 6 off * 62%/70
1.00% 0.50%
1.26 0.63
4.43 5.31
__________
6.69% 6,44% 6.69+6.44= 13.13 6.69/13.13= 51.0%/49.0% in favor of finesse. 51/49=1.04
But we also know that W didn't choose a spade so we reduce our probabilities due to restricted choice. If W had Hxxx or Hxx in both Spades and diamonds he would choose either suit only 50%, similarly if he had only low cards in both suits he would choose either suit 50%.
Assuming the spades split 4-4 and only counting akqj as honors there are 32 cases has a 2 or more card sequence, 20 cases of a A with no K, 17 cases of Hxxx or other HHxx, and one txxx. Since W led the 4 of ♦ we deduce that he did not have a spade sequence, we must reduce the diamond % of Hxxx and Hxx leads by 50% * percentage of spade Hxx(x)(x), and the diamond % of x(x)(x)(x) by 50% the percentage of possible spade xxxx leads, It is presumed that the opponents would overcall if they had 5 cards or more with 10 hcps.

6.69% *( 1- 1/2 (17/50))= 5.55%
6.44% * (1- 1/2 (1/50)= 6.38%
finesse now on 5.55/11.93= 46.5+ or 47% So we would not take it. odds 46.5/ 53.5 = .87

Next we can compare the a priori odds based on the cards with our knowledge of our customers. If we know W is a good student of US Bridge World, we can deduce that he prefers Kxx(x)(x) lead to quack xx(x)(x) leads. If they are European we will go with the odds that they would follow Bird-Anthias, and avoid higher Hxx(x)(x) leads. Otherwise, we will weigh our bets based on probability the a priori case that he will not care.

[whereagles]

mikeh, on 2015-January-20, 18:24, said:

I know players over here (all bad) who also seem to think that underleading a K is terrible. I think some of them think it better to underlead an Ace!

If I were the leader, the odds are 98% that the hook will work

That has actually been food for thought for a long time now. I'm not completely sure but I think historically it went like this:

1. Borel/Cheron's book (of 194x) calculated theoretical odds for A, K, Q and J underleads on abstract suits. The risk of blowing a trick was higher for K, then A (lower if the A itself was led), then Q and finally J. Because of this, people shone from K underleads for a long time.

2. Then for some reason lore has developed calling for more Hxx underleads. This was probably due to increase of auction precision and consequent pinpointing of long suits for discards, a situation which does call for aggressive leads.

3. Finally, Bird/Anthias simulations calculated real odds for Hxx underleads and found out that in practice Hxx underlead risks are in fact close to the original Borel/Cheron odds, and curiously seem to hold even for some situations when dummy is known to have a long suit.

What I make of the above, purely on statistical grounds, is that king underleads are to be avoided unless you have a clear reason to make it. (Say opps play 4M after a 3x fit-bid or so.)

[Zelandakh]

mikeh, on 2015-January-20, 18:24, said:

If I were the leader, the odds are 98% that the hook will work

You realise this has gone into Phil's notes to counteract your passing him out on the walk-the-dog hands!

[down1xx]

eagles123, on 2015-January-18, 13:57, said:

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lead is the 4 of ♦

finesse or not?

Thanks,

Eagles

no don't finesse...pull trump throw away a spade after cash q♣ a♣ k♣ and give up 1d and 1spade
if finesse loses you will only make 4(1♦ and 2♠) losers the overtrick makes it not worth the risk!!