[gnasher]

gwnn, on 2011-February-24, 03:10, said:

But is it really likely, for instance, that partner has 0 or 1 spade?

Probably not, but it's also not that likely that he has four spades and a hand that would pass a takeout double. Two and three are quite likely numbers.

[jogs]

Fluffy, on 2011-February-24, 09:21, said:

your partner is one of those like me that like to apss and then punish partner for reopning lol.

Plenty of players play that way. Very few admit it.

[bluecalm]

After looking at some generated hands my opinion is now that 4♠ is the worst bid by far.
Double and pass are close but double is a bit better.

EDIT: I've changed my mind again; my friend pointed out that I estimated 4M opener range wrong. I assumed it's purely preemptive while many people open (semi)constructive hands that way.
After this adjustment I am convinced pass is the best action and it's not particularly close.

[han]

I think that 4S is considerably better than double. I would almost go as far as saying that double is a strange call that few would consider at the table, but for some strange reason looks attractive on a forum.

Passing over 4H and then jumping to slam should be forbidden. You should put a rule in your system book: we do not jump to slam after partner's first call in balancing seat. An obvious exception to this rule is when partner shows strength by jumping.

[655321]

bluecalm, on 2011-March-05, 14:49, said:

After looking at some generated hands my opinion is now that 4♠ is the worst bid by far.
Double and pass are close but double is a bit better.

EDIT: I've changed my mind again; my friend pointed out that I estimated 4M opener range wrong. I assumed it's purely preemptive while many people open (semi)constructive hands that way.
After this adjustment I am convinced pass is the best action and it's not particularly close.

First you said 4♠ was best, then you said Double was best, now Pass 'is the best action and it's not particularly close'! (I recall that in another thread you bragged that your intuition is "quite well founded though by analyzing tons of vugraph hands"). Here is a challenge for you. Find some vugraph hands with a singleton heart where good players passed out a 4♥ opening. What is the strongest hand with 5 spades and 1 heart that a good player passed with? I wonder if there will be any such hands at all.

[gnasher]

Han's certainty surprised me enough to make me do a simulation. I gave South 0-12 HCP and:
- Any 9+-card suit
- An 8-card suit, with at least 2 of the top 5
- 7-4 or more extreme, with at least 2 of the top 5

Then I took the first 20 deals that I thought consistent with the bidding, and decided what would happen on each. That gave me

4S > Pass > Double: 2 deals
Double > Pass > 4S: 2 deals
Pass > 4S > Double: 1 deal
Pass > Double > 4S: 2 deals
Double = 4S, either > Pass : 10 deals
All equal, or can't decide what would happen: 3 deals

From this I conclude that I should have looked at more hands, but pass is probably not right. Also that phrases like "considerably better", "not particularly close", "worst bid by far", and "doesn't seem very close" don't belong in his thread.

Here are the hands and my analysis:

      	S: T986
      	H: 86
      	D: A75
      	C: A765
 S: ---        	S: AKJ75
 H: J43        	H: 2
 D: KQJT9      	D: 8642
 C: KJT84      	C: Q93
      	S: Q432
      	H: AKQT975
      	D: 3
      	C: 2
Double > Pass > 4S
--------------------------
      	S: Q964
      	H: A3
      	D: KJ5
      	C: KJ85
 S: T82        	S: AKJ75
 H: 54 			H: 2
 D: T7 			D: 8642
 C: AT7642 		C: Q93
      	S: 3
      	H: KQJT9876
      	D: AQ93
      	C: ---
Probably too strong for 4H
Pass > Double > 4S
--------------------------
      	S: 642
      	H: K96
      	D: AQT
      	C: KT62
 S: T983   		S: AKJ75
 H: 43 			H: 2
 D: KJ 			D: 8642
 C: AJ854      	C: Q93
      	S: Q
      	H: AQJT875
      	D: 9753
      	C: 7
Double/4S > Pass
--------------------------
      	S: T964
      	H: K4
      	D: AKQT
      	C: K64
 S: 83 			S: AKJ75
 H: J5 			H: 2
 D: J75        	D: 8642
 C: AT8752 		C: Q93
      	S: Q2
      	H: AQT98763
      	D: 93
      	C: J
Pass > Double > 4S
--------------------------
      	S: 9432
      	H: Q5
      	D: KT5
      	C: AT86
 S: QT6        	S: AKJ75
 H: JT 			H: 2
 D: AQJ7   		D: 8642
 C: KJ42   		C: Q93
      	S: 8
      	H: AK987643
      	D: 93
      	C: 75
4S > Pass > Double (assumed West leaves in the double)
--------------------------
      	S: QT6
      	H: K
      	D: J95
      	C: AKT742
 S: 42 			S: AKJ75
 H: 975        	H: 2
 D: AKQ73      	D: 8642
 C: J65        	C: Q93
      	S: 983
      	H: AQJT8643
      	D: T
      	C: 8
Pass > 4S > Double
--------------------------
      	S: QT93
      	H: K3
      	D: AJ97
      	C: 872
 S: 842        	S: AKJ75
 H: A75        	H: 2
 D: KQT5   		D: 8642
 C: AT5        	C: Q93
      	S: 6
      	H: QJT9864
      	D: 3
      	C: KJ64
Double > pass > 4S
--------------------------
      	S: 3
      	H: A5
      	D: AQ73
      	C: AK7542
 S: QT964      	S: AKJ75
 H: Q7 			H: 2
 D: KT95   		D: 8642
 C: J8 			C: Q93
      	S: 82
      	H: KJT98643
      	D: J
      	C: T6
North might have moved over 4H
Double/4S > Pass (assumed N will bid 5H)
--------------------------
      	S: Q2
      	H: K4
      	D: A5
      	C: KT87652
 S: T983   		S: AKJ75
 H: Q9 			H: 2
 D: QJT7   		D: 8642
 C: AJ4        	C: Q93
      	S: 64
      	H: AJT87653
      	D: K93
      	C: ---
All actions equal (W removes double to 4S; N bids 5H)
--------------------------
      	S: T942
      	H: JT
      	D: AKQT93
      	C: K
 S: Q8 			S: AKJ75
 H: 965        	H: 2
 D: J75        	D: 8642
 C: A8765      	C: Q93
      	S: 63
      	H: AKQ8743
      	D: ---
      	C: JT42
4H would probably make, but unclear whether N would double 4S or 5C
--------------------------
      	S: QT8
      	H: 973
      	D: A93
      	C: K542
 S: 9432   		S: AKJ75
 H: KT 			H: 2
 D: K7 			D: 8642
 C: AJT86      	C: Q93
      	S: 6
      	H: AQJ8654
      	D: QJT5
      	C: 7
Double/4S > Pass
--------------------------
      	S: 943
      	H: 43
      	D: KT3
      	C: J8742
 S: QT86   		S: AKJ75
 H: A75        	H: 2
 D: A7 			D: 8642
 C: AT65   		C: Q93
      	S: 2
      	H: KQJT986
      	D: QJ95
      	C: K
Double/4S > Pass
--------------------------
      	S: QT2
      	H: Q4
      	D: KQT
      	C: KT875
 S: 98643      	S: AKJ75
 H: K63        	H: 2
 D: 53 			D: 8642
 C: AJ2        	C: Q93
      	S: ---
      	H: AJT9875
      	D: AJ97
      	C: 64
Double/4S > Pass
--------------------------
      	S: 32
      	H: KT
      	D: JT95
      	C: AKJ65
 S: QT94   		S: AKJ75
 H: J97        	H: 2
 D: AKQ73      	D: 8642
 C: 8          	C: Q93
      	S: 86
      	H: AQ86543
      	D: ---
      	C: T742
Double/4S > Pass
--------------------------
      	S: QT2
      	H: 98
      	D: KJT5
      	C: AT65
 S: 98643      	S: AKJ75
 H: AT4        	H: 2
 D: A93        	D: 8642
 C: KJ 			C: Q93
      	S: ---
      	H: KQJ7653
      	D: Q7
      	C: 8742
Double/4S > Pass
--------------------------
      	S: T3
      	H: Q8
      	D: J53
      	C: KJT652
 S: Q96        	S: AKJ75
 H: T4 			H: 2
 D: AQT97      	D: 8642
 C: A74        	C: Q93
      	S: 842
      	H: AKJ97653
      	D: K
      	C: 8
4S > Pass > Double
--------------------------
      	S: QT932
      	H: K985
      	D: AJ
      	C: K6
 S: 864        	S: AKJ75
 H: 4          	H: 2
 D: K9753      	D: 8642
 C: AJ52   		C: Q93
      	S: ---
      	H: AQJT763
      	D: QT
      	C: T874
NS make 5H, but unclear what would happen after 4S
--------------------------
      	S: Q92
      	H: T43
      	D: JT
      	C: KT852
 S: T864   		S: AKJ75
 H: AK 			H: 2
 D: AQ9753 		D: 8642
 C: 4          	C: Q93
      	S: 3
      	H: QJ98765
      	D: K
      	C: AJ76
Double/4S > Pass
--------------------------
      	S: QT63
      	H: J5
      	D: T
      	C: AT8764
 S: 942        	S: AKJ75
 H: A3 			H: 2
 D: AK9753 		D: 8642
 C: J2 			C: Q93
      	S: 8
      	H: KQT98764
      	D: QJ
      	C: K5
Double/4S > Pass
--------------------------
      	S: 9
      	H: K
      	D: QJT53
      	C: KJT764
 S: QT6432 		S: AKJ75
 H: 986        	H: 2
 D: K          	D: 8642
 C: A52        	C: Q93
      	S: 8
      	H: AQJT7543
      	D: A97
      	C: 8
Double/4S > Pass

Edit: I threw out eight deals because South didn't have a 4♥ opener:
T986 KJ97543 Q 2
2 AT87543 T T862
9432 AK98764 T 8
T642 JT87543 --- AJ
62 AKJT9863 --- AT4
9 KQT7653 5 AK42
9 QJT9743 J753 6
QT93 KJT8763 Q 4
and five because West would have acted:
T94 4 AK3 AKT854
Q864 A6 KQJ9 KT6
T843 4 A9 AKJ842
QT6 AJ AKJ9 A742
Q62 5 AJT97 AKT7

Here is my code:

east is "AKJ75 2 8642 Q93"

main {
  accept if {[open_4 south hearts]}
  reject
}

proc open_4 {hand suit} {
  set cards [$suit $hand]
  set ptn [$hand pattern]
  set t5 [Top5 $hand $suit]
  
  reject if {[hcp $hand] > 12}
  accept if {$cards > 8}
  reject if {$cards < 7}
  reject if {$t5 < 2}
  accept if {$cards > 7 || $ptn == "7 4 1 1" || $ptn == "7 4 2 0" || $ptn == "7 5 1 0" || $ptn == "7 6 0 0"}
  reject
  } 

This post has been edited by gnasher: 2011-March-07, 02:58

[MrAce]

655321, on 2011-March-06, 17:08, said:

First you said 4♠ was best, then you said Double was best, now Pass 'is the best action and it's not particularly close'!

I will put this to my forum signature !

[han]

gnasher, on 2011-March-06, 19:19, said:

4S > Pass > Double: 2 deals
Double > Pass > 4S: 2 deals
Pass > 4S > Double: 1 deal
Pass > Double > 4S: 2 deals
Double = 4S, either > Pass : 10 deals
All equal, or can't decide what would happen: 3 deals

From this I conclude that I should have looked at more hands, but pass is probably not right.

Thanks for your post Andy. I started doing a simulation yesterday but soon decided that to do it well I'd have to spend more effort than I was willing at the time. I find your results very interesting, I didn't expect pass to be this much worse.

I think your requirements for the 4H opening are a little more strict than what I would use. I find this an interesting topic and perhaps we could agree on the method to analyse these hands, and then both do a simulation to see if we get similar answers. Which hands pull our double to 4S, which hands pass, and which east hands double our 4S? Do we just look at the hands and apply "common sense"?

[gnasher]

han, on 2011-March-07, 03:27, said:

Thanks for your post Andy. I started doing a simulation yesterday but soon decided that to do it well I'd have to spend more effort than I was willing at the time. I find your results very interesting, I didn't expect pass to be this much worse.

I think your requirements for the 4H opening are a little more strict than what I would use. I find this an interesting topic and perhaps we could agree on the method to analyse these hands, and then both do a simulation to see if we get similar answers. Which hands pull our double to 4S, which hands pass, and which east hands double our 4S? Do we just look at the hands and apply "common sense"?

I don't think my constraints for the 4♥ opener were a particualrly good reflection of what I'd do at the table. I also found it quite hard work to apply common sense, both in filtering out the unwanted deals and in deciding what would happen after particular actions. Looking again at some of the hands I rejected as not being 4♥ openers, I'm not sure that I even agree with myself.

On the other hand, trying to write code to reflect the decisions of South, West and North in code would be a nightmare, so I think that some inspection of the hands will be necessary.

Let's start with the 4♥ opener, because it's easy. What changes would you make to my constraints, and which of my rejects would you want to include?

[han]

I often see people opening 4H with 7321 distribution and quite good suits. I agree that it is too difficult to write code for when partner pulls a double, and for when RHO doubles. But we should have some idea of when partner bids 4S with a balanced hand and 4 spades. That is quite a common hand type. Would partner for example do it with something like QJx in hearts? That's an interesting question in its own right.

When will the opponents double 4S? And when will partner pull the double to 5m? Those are also relevant questions. We could agree that partner always pulls to a 7-card suit if he has short spades, and also pulls with a 6-card minor and a spade void. With a good 7-card minor and a spade void partner should pull even without a double (and yes, I play that is natural, and I think it should be).

When will the opponents double? Probably not as often as they should. Perhaps only when RHO has an opening hand with 4+ spades, or with 2-3 spades and 15+? Of course with some of these hands the opponents will bid 5H instead.

[gnasher]

han, on 2011-March-07, 06:16, said:

I often see people opening 4H with 7321 distribution and quite good suits.

I do that too, but I was trying to model what the majority on this forum would regard as mainstream. Perhaps I overcompensated.

How about including 7321 types which have three of the top four (KQJxxxx or better)? Should we consider side values too?

Quote

I agree that it is too difficult to write code for when partner pulls a double, and for when RHO doubles. But we should have some idea of when partner bids 4S with a balanced hand and 4 spades. That is quite a common hand type. Would partner for example do it with something like QJx in hearts? That's an interesting question in its own right.

I would normally take out a takeout double with any of these:
- Five spades
- Four spades and no heart trick (maybe not if 4333 and poor spades)
- A 6-card minor (maybe not if I had a heart trick)
- 5-5 in the minors
- 31(54)
- 22(54) with good suits

Quote

When will the opponents double 4S? And when will partner pull the double to 5m? Those are also relevant questions. We could agree that partner always pulls to a 7-card suit if he has short spades, and also pulls with a 6-card minor and a spade void.

I'm not sure how often this will matter - if we're close to making 5m we probably won't be doubled in 4♠.

Quote

With a good 7-card minor and a spade void partner should pull even without a double (and yes, I play that is natural, and I think it should be).

I think that's reasonable, certainly in a style where you would bid 4♠ on the hand in the original post. Presumably, though, some of these hands would not have passed over 4♥.

(Edited because I'd misunderstood some of Han's comments the first time I read them.)

This post has been edited by gnasher: 2011-March-07, 13:47

[hrothgar]

gnasher, on 2011-March-06, 19:19, said:

Han's certainty surprised me enough to make me do a simulation.

FWIW, I really like Gnasher's post

In particular, providing

1. The code
2. The complete set of hands
3. The underlying assumptions

makes it very easy to see how he approached the problem

[jogs]

gnasher, on 2011-March-06, 19:19, said:

Han's certainty surprised me enough to make me do a simulation. I gave South 0-12 HCP and:
- Any 9+-card suit
- An 8-card suit, with at least 2 of the top 5
- 7-4 or more extreme, with at least 2 of the top 5

Then I took the first 20 deals that I thought consistent with the bidding, and decided what would happen on each. That gave me

4S > Pass > Double: 2 deals
Double > Pass > 4S: 2 deals
Pass > 4S > Double: 1 deal
Pass > Double > 4S: 2 deals
Double = 4S, either > Pass : 10 deals
All equal, or can't decide what would happen: 3 deals

From this I conclude that I should have looked at more hands, but pass is probably not right. Also that phrases like "considerably better", "not particularly close", "worst bid by far", and "doesn't seem very close" don't belong in his thread.

I suspect if you ran 1000 or more iterations, the mostly likely number of spades held by West would be three. West wouldn't bid 4S after a double with only three spades. The total number of spades would be higher than diamonds or clubs. Also only spades can be bid on the four level. I think 4S would fare better than double.

[gnasher]

jogs, on 2011-March-07, 14:53, said:

I suspect if you ran 1000 or more iterations, the mostly likely number of spades held by West would be three. West wouldn't bid 4S after a double with only three spades. The total number of spades would be higher than diamonds or clubs. Also only spades can be bid on the four level. I think 4S would fare better than double.

You seem to assume that when partner has three spades we want to be in 4♠. I think that's quite a questionable assumption.

Anyway, ask and it shall be given. Over 10,000 deals:

 West 0 spades   = 110
 West 1 spades   = 771
 West 2 spades   = 2039
 West 3 spades   = 3065
 West 4 spades   = 2512
 West 5 spades   = 1162
 West 6+ spades  = 341

source format/none
source lib/utility.tcl

east is "AKJ75 2 8642 Q93"

set w_0s  0
set w_1s  0
set w_2s  0
set w_3s  0
set w_4s  0
set w_5s  0
set w_6s  0

main {
  if {[open_4 south hearts]} {
	set len [spades west]
	
	if {$len == 0} {
  	incr w_0s
	} elseif {$len == 1} {
  	incr w_1s
	} elseif {$len == 2} {
  	incr w_2s
	} elseif {$len == 3} {
  	incr w_3s
	} elseif {$len == 4} {
  	incr w_4s
	} elseif {$len == 5} {
  	incr w_5s
	} else {
  	incr w_6s
	} 
	
  accept
  }
  
  reject
}

proc open_4 {hand suit} {
  set cards [$suit $hand]
  set ptn [$hand pattern]
  set t5 [Top5 $hand $suit]
  
  reject if {[hcp $hand] > 12}
  accept if {$cards > 8}
  reject if {$cards < 7}
  reject if {$t5 < 2}
  accept if {$cards > 7 || $ptn == "7 4 1 1" || $ptn == "7 4 2 0" || $ptn == "7 5 1 0" || $ptn == "7 6 0 0"}
  reject
}

deal_finished {
  puts " West 0 spades   = $w_0s"
  puts " West 1 spades   = $w_1s"
  puts " West 2 spades   = $w_2s"
  puts " West 3 spades   = $w_3s"
  puts " West 4 spades   = $w_4s"
  puts " West 5 spades   = $w_5s"
  puts " West 6+ spades  = $w_6s"
}

[Fluffy]

{comments}

---

Not the exact same shape, but curious that the only thing that stopped -500 even when I had 5 trump support and 4 diamond support was that the shortness in diamonds was also short in trumps