[mikeh]

gnasher, on May 21 2010, 03:03 AM, said:

Fluffy, on May 20 2010, 11:14 PM, said:

once you know partner has ♠Kxxx but equally likelly ♠KJxx or ♠K10xx anyone knows what the percentage for 4 spade tricks is?

There are 9 spades excluding the AKQ5, and partner has 3 of them. Hence he will have:
KJxx 3/9 of the time = 1/3
K10xx 6/9 x 3/8 of the time = 1/4
Kxxx 6/9 x 5/8 of the time = 5/12

With K10xx, playing from the top and taking a marked finesse when they're 5-1 is about 61%. Adding a bit for card-reading, let's call it 65%. Without the 10, you make when they're 3-3, or 36% of the time.

Hence you make: 1/3 + 1/4 x .65 + 5/12 x .36 = 65%

plus a fraction for K9xx opposite AQx for stiff J/10 offside or playing for restricted choice when LHO has Jx/10x...or flat out making when either opp has J10 tight(note however that with this K9xx holding, we will sometimes go down when the suit is 3-3, thus meaning that we have to slightly reduce our assessment of 3-3 chances)

[ONEferBRID]

cherdanno, on May 21 2010, 01:04 AM, said:

awm, on May 20 2010, 11:13 PM, said:

Openers natural rebids after 4sf aren't very well optimized. In the auction here of:

1♣-1♥-1♠-2♦

Opener having five spades will be quite rare yet a cheap bid of 2♠ is reserved for it. Opener having three hearts is also rare, especially if you often raise with minimum 4315 patterns (admittedly some will rebid 2♥ here on 4225 with a heart honor too but this just raises frequency a little). In comparison opener's 4036/4126/4216/4xx7 patterns (all of which presumably bid 3♣) are quite common. It seems like poor use of space especially since when opener has these patterns you often want to try for slam in clubs.

Just a thought about a spot where some alternative methods might help.

A simple fix is to allow 2♥ rebids with 4225, and to invert the 2♠ and 3♣ rebids.

I like the idea of 2S! as a sort of catchall bid to make more efficient use of the bidding space.... instead of bidding 3C over 2D! ( 4th Suit GF ) .

A similar treatment is described in Hardy's infamous yellow book under "Opener's least probable rebid after 4SGF ". His treatment was to aid in the problem hands when Opener had a 4-4 or a 5-6 ( Sp/Cl ) with no 3 card Ht support and no Diam-stop... as an example.

1C - 1H
1S - 2D!
2S! - say 2NT
??
3S = the 5/6 hand whereas any other rebid by Opener showed the 4/4 s/c
3C/3D/3H = 4s/4c w/o 3h and no Diam-stop since no 2H or 2NT were bid over 2D!

- - - - - - - - - - - - - - - - - - - - - - - -
On the given hand since 1S shows at least a 4/5, then:
1C - 1H
1S! - 2D!
2S! - say 2NT
??
3C = 4/6 whereas
3S = 5/6 and
3H/3D/3NT would show the 4/5 without 3♥ and no ♦-stop ( if no 2H or 2NT bid were rebid directly over 2D! )

[Fluffy]

mikeh, on May 21 2010, 03:18 PM, said:

gnasher, on May 21 2010, 03:03 AM, said:

Fluffy, on May 20 2010, 11:14 PM, said:

once you know partner has ♠Kxxx but equally likelly ♠KJxx or ♠K10xx anyone knows what the percentage for 4 spade tricks is?

There are 9 spades excluding the AKQ5, and partner has 3 of them. Hence he will have:
KJxx 3/9 of the time = 1/3
K10xx 6/9 x 3/8 of the time = 1/4
Kxxx 6/9 x 5/8 of the time = 5/12

With K10xx, playing from the top and taking a marked finesse when they're 5-1 is about 61%. Adding a bit for card-reading, let's call it 65%. Without the 10, you make when they're 3-3, or 36% of the time.

Hence you make: 1/3 + 1/4 x .65 + 5/12 x .36 = 65%

plus a fraction for K9xx opposite AQx for stiff J/10 offside or playing for restricted choice when LHO has Jx/10x...or flat out making when either opp has J10 tight(note however that with this K9xx holding, we will sometimes go down when the suit is 3-3, thus meaning that we have to slightly reduce our assessment of 3-3 chances)

and if he has ♦Q or ♦J there are possible mencaes in both red suits for a squeeze, all in all close to 70% so a coin toss.

[gnasher]

Fluffy, on May 22 2010, 01:18 PM, said:

and if he has ♦Q or ♦J there are possible mencaes in both red suits for a squeeze, all in all close to 70% so a coin toss.

I can't see how you can use the hearts in any squeeze. You might have a diamond-spade squeeze, by ruffing three hearts in the long hand. I suspect that you're overestimating the combined value of that and of Mike's additions.

[jdonn]

Gnasher I think you have to add a lot more for card reading! You essentially said we will only finesse for Jxxx onside when it's right 1 out of 10 times. I would like to think we can do a little better.

[gnasher]

jdonn, on May 22 2010, 08:31 PM, said:

Gnasher I think you have to add a lot more for card reading! You essentially said we will only finesse for Jxxx onside when it's right 1 out of 10 times. I would like to think we can do a little better.

Did I?

Assume that it's K1032 opposite AQ4. We ruff three hearts whilst drawing trumps, then cash ♠AQ and lead another one.

43% of the time (half of the 3-3s, 1/3 of the 4-2s, 7/12 of the 5-1s, and 1/2 of the 6-0s) we'll already have made, because we'll have seen the jack or it will be marked onside.
23% of the time we'll already be down, because LHO started with Jxxx(+)
16% of the time RHO will have Jx left
18% LHO will have the bare jack left

I estimated that we'd make it 65% of the time. That means that on the 34% of deals where we face a guess, we will get it right on 22%, whereas playing mechanically we'd manage only 18%.

[Flame]

A good system might identify that the A♥ is wasted and stop at 6, while less good system might not find that out and get to 7.
I don't think being at 7 should get too much credit here unless you found out about the J♠

[barryallen]

Flame, on May 23 2010, 06:39 AM, said:

A good system might identify that the A♥ is wasted and stop at 6, while less good system might not find that out and get to 7.
I don't think being at 7 should get too much credit here unless you found out about the J♠

Watching Brink-Drijver over the last few months and have seen similar hands bid to the grand with ease. It just appears that these slams are only put on here as an advert for the strong club approach.