jdonn Posted March 6, 2010 Report Share Posted March 6, 2010 strikes me as a pretty good case in point. About half of the responders to this thread led a spade - which is a pathetic 7 to 1 underdog. :D :D :D And they are such accurate constraints too :( Quote Link to comment Share on other sites More sharing options...
OleBerg Posted March 6, 2010 Report Share Posted March 6, 2010 Where this is headed: Quote Link to comment Share on other sites More sharing options...
karlson Posted March 6, 2010 Report Share Posted March 6, 2010 You know, every once in a while someone comes along with a didactic and slightly condescending posting style, and tells us that we all suck at bridge. Now oftentimes the bridge arguments are laughably and provably wrong (think: foo), and it's not worth paying attention to. But sometimes they have a valid bridge point, and I don't see why the rhetoric should distract us. I know many people like the spade lead, but mostly it's a matter of instinct, no one has a particularly convincing argument. Everyone is guessing, as they should be, since no one ever has enough datapoints from experience here. When the simulation(*) suggests so strongly that the spade lead is wrong, whatever caveats you apply to the DD analysis, I think it's worth rethinking. And I admit that on this hand I'm convinced. Neither declarer nor dummy is likely enough to have an outside source of tricks, and if they're marginal on high cards, one trick from the lead will often be enough. (*)I've redone the sims with what I think are slightly more accurate constraints (gave 2n bidder 2245 hands, put an upper range on hcp, didn't let responder have 5-5 or 4-5 in the majors, tried to take away some hands that would texas. I didn't try to model what exactly the 5d bid should look like.) The spade still comes out at least a 3-1 to 4-1 underdog. You can look at hands here. (**) ok, I noticed one bug, I only looked for leads that led to -1, sometimes there will be some leads for -2 that don't show up. If you think that this unfairly biases against a spade lead, I think you're crazy, but of course I'll redo it. Quote Link to comment Share on other sites More sharing options...
rogerclee Posted March 6, 2010 Report Share Posted March 6, 2010 I called jdeegan an idiot, and I stand by that statement (this thread does little to counter that). However, I never said I thought his arguments for a spade lead were baseless. In fact in my first post I actually thought it was somewhat close (spade or club). It should be noted that among my friends, I am probably the least likely to lead aggressively (underlead a K in particular) against a small slam where I think my RHO is strong. Anyway I have no problem with being told that a computer simulation probably says a club is right. It's certainly more convincing than anything else so far. Quote Link to comment Share on other sites More sharing options...
gwnn Posted March 6, 2010 Report Share Posted March 6, 2010 I can't help but notice that most slams in karlson's simulation are terrible. Like responder cooperating with xxJ9xxxAQTxxx and then surprise, a spade lets it through. I am unhappy with these opponents and don't think most real life opps of reasonable quality would bid like this. Maybe it's just because I'm biased for underleading honours or against condescending posts. Quote Link to comment Share on other sites More sharing options...
gnasher Posted March 6, 2010 Report Share Posted March 6, 2010 I can't help but notice that most slams in karlson's simulation are terrible. Like responder cooperating with xxJ9xxxAQTxxx and then surprise, a spade lets it through. I am unhappy with these opponents and don't think most real life opps of reasonable quality would bid like this. If they reach a slam which requires either a king onside or an underlead of the relevant king, and you'll nearly always lead from a king if you have one, doesn't that make it quite a good slam? Quote Link to comment Share on other sites More sharing options...
gwnn Posted March 6, 2010 Report Share Posted March 6, 2010 good point. I will need to look at the hands again. Quote Link to comment Share on other sites More sharing options...
karlson Posted March 6, 2010 Report Share Posted March 6, 2010 I can't help but notice that most slams in karlson's simulation are terrible. Like responder cooperating with xxJ9xxxAQTxxx and then surprise, a spade lets it through. I am unhappy with these opponents and don't think most real life opps of reasonable quality would bid like this. Maybe it's just because I'm biased for underleading honours or against condescending posts. Remember also that you're only looking at the ones that are beatable at all. Quote Link to comment Share on other sites More sharing options...
jdeegan Posted March 7, 2010 Author Report Share Posted March 7, 2010 I called jdeegan an idiot, and I stand by that statement (this thread does little to counter that). :D :D :D At last something we can all agree on. You only agree with my wife and most of my bridge partners. Two or three years ago this thread was a treasure for serious players, but imho it has been going down hill lately. Back then, whenever I had a bridge hand that baffled me (and they came up all the time), I would submit it and learn something useful. Nowdays, the post-mortem discourse is sometimes little better than one finds at the average suburban duplicate club. I just wanted to stir things up a little. :D :D :D Quote Link to comment Share on other sites More sharing options...
jdonn Posted March 7, 2010 Report Share Posted March 7, 2010 I can't help but notice that most slams in karlson's simulation are terrible. Like responder cooperating with xxJ9xxxAQTxxx and then surprise, a spade lets it through. I am unhappy with these opponents and don't think most real life opps of reasonable quality would bid like this. Maybe it's just because I'm biased for underleading honours or against condescending posts. Remember also that you're only looking at the ones that are beatable at all. Something is still obviously wrong with the constraints. You have some, for example 2 and 8, where south is super-accepting on average (at best) 22 counts that clearly aren't worth it. You have others, for example 4 and 9, where south would rebid 2♠ with his 5-4 in the majors (at least most would). And you have quite a lot where I just don't believe responder would try for slam at all (1, 5, 11, 13, 24, etc.) And I believe all of those flaws are generally bad for a spade lead. Obviously if south has spades that is bad, and if NS are stretching a lot then rather than a need to take advantage of whatever strength we have, we more often have a need to not give anything up. What were your constraints exactly? They certainly don't match the ones given in this challenge. Quote Link to comment Share on other sites More sharing options...
effervesce Posted March 7, 2010 Report Share Posted March 7, 2010 Out of interest, after the transfer, superaccept, what did their 5♦ bid mean (apart from cuebid)? Possible options:1) Looking for a specific control (perhaps denying a club control)2) Shortage3) A sidesuit I'd rule out option 1, since opener superaccepted: on a 2♣ opener the superaccept direct to 4♥ should show a control in each suit, as otherwise the opener could have cuebid something else as a superaccept. Two is possible, and possibly the best method. For option 3, where it shows a sidesuit, I think a spade lead would be much better than what the previous simulations have suggested as a passive lead can lead to spade losers being ditched on dummy's diamonds. Quote Link to comment Share on other sites More sharing options...
karlson Posted March 7, 2010 Report Share Posted March 7, 2010 First I gave south 22-24 balanced (4333,4432,5332) with 4+ hearts, a spade control, and a club control, responder 5+ hearts, and NS 31+ hcp, which was basically the original constraint except that I didn't make the superaccept very restrictive. Then I restricted responder's hands a bit. Gave him no 4-5 or 5-5 majors or 7 hearts, and gave him 9+ hcp or 8 or fewer losers. Allowed opener to have some 4522 shape also (hence those 4-5 majors hands). Now I've tried a couple other things. I've beefed up opener, as you suggested (and the op said too). Gave him 23-24 with at least 8 controls, and at least 6 hcp in hearts. Took away the 4-5 and 5-4 majors hands. I've tried giving responder real diamonds (4+). I've also tried beefing up responder, giving him only 7-loser or better (or 9+hcp) hands, with real diamonds. hands. The spade never comes close to being a favorite. We can pick more at criteria, but I don't believe that slight changes are going to change it from a huge underdog to a favorite. Moreover, as far as I can see, most of these hands are pretty easy to play, so I don't think there's a huge DD bias, but of course one can always argue with that. Quote Link to comment Share on other sites More sharing options...
effervesce Posted March 7, 2010 Report Share Posted March 7, 2010 Ok kalson,I manually analysed the first 50 hands of your link (from the post above).Given the constraints that opener would cuebid if missing a 1st/2nd round control in a suit (ie opener cuebids in a suit if missing AK in another suit), and my analysis of hands that would cuebid 5D as responder (if responder only bids 5D as showing a suit), I get the following results 1 - good, spade only lead2 - good, spade only lead3 - opener does not superaccept 4H - cuebids 3S4 - opener cuebids 3S5 - opener cuebids 4C6 - opener cuebids 4C7 - opener cuebids 4C8 - opener cuebids 4C9 - opener cuebids 4C10 - good, non-spade11 - cuebids 4C12 - cuebids 4C13 - cuebids 3S14 - cuebids 4C15 - good, spade only lead16 - cuebids 3S17 - good, spade only lead18 - cuebids 4C19 - good, non-spade20 - dont think responder would cuebid 5D over 4H21 - good, non-spade22 - good, spade only lead23 - good, spade only24 - opener cuebids25 - good, any lead26 - opener cuebids27 - opener cuebids28 - good, spade only lead29 - good, non-spade30 - opener cuebids31 - opener cuebids32 - good, non-spade33 - opener cuebids34 - opener cuebids35 - opener cuebids36 - opener cuebids37 - opener cuebids38 - dont think responder would cuebid 5D39 - opener cuebids40 - good, spade only lead41 - partner will lightner double!42 - good, any lead43 - opener cuebids44 - good, non-spade45 - opener cuebids46 - dont think responder would cuebid 5D47 - opener cuebids48 - opener cuebids49 - good, club only lead50 - opener cuebids That is, only 17 hands of the 50 qualify. Of the 17, 8 only a spade will beat it, 6 any non-spade, one only a club lead, 2 any lead. Now, this is even with significant bias in the hands you gave - all of these are settable double dummy. When single dummy, ie when declarer won't know the diamond layout, I'd bet there are many more hands where a spade lead is best compared to other leads where a spade lead is necessary to set up a trick before spades are pitched on diamonds. With responder having hearts+diamonds I'll have to disagree with you and say that there would be a HUGE double dummy bias. Quote Link to comment Share on other sites More sharing options...
effervesce Posted March 7, 2010 Report Share Posted March 7, 2010 Ok I've analysed the hands 51-100 and I get 51 - opener cuebids52 - good, any non-spade53 - good, any lead54 - good, non-spade55 - lightner double56 - responder does not cuebid 5D57 - good, spade only58 - good, non-spade59 - good, diamond only60 - good, spade only61 - good, non-spade62 - responder does not cuebid 5D63 - lightner X for dummy's sidesuit?64 - good, non-spade65 - good, any66 - responder does not cuebid 5D67 - opener cuebids68 - good, club only69 - opener cuebids70 - opener cuebids71 - good, non-spade lead72 - opener cuebids73 - opener cuebids75 - lightner X?76 - good, non-spade lead77 - opener cuebids78 - good, club only lead79 - opener cuebids80 - good, diamond only lead81 - good, spade only lead82 - good, spade only lead83 - dont think responder bids 5D84 - opener cuebids85 - good, club only lead86 - dont think responder cuebids 5D87 - dont think responder cuebids 5D88 - good, spade only lead89 - good, spade only lead90 - opener cuebids91 - good, spade only lead92 - opener cuebids93 - good, non-spade only94 - good, spade only95 - opener cuebids96 - lightner X!97 - opener cuebids98 - good, non-spade lead only99 - lightner X?100 - lightner X! 24 hands qualify, of which 7 only a spade works, 2 any lead, 8 non-spade, 2 diamond only, 3 club only Summary: out of 41 qualifying hands from the first 100 hands from Karlson's link , 15 only a spade works, 14 only a non-spade works, 2 diamond only, 4 club only, 4 any lead.And that's without taking into account any double-dummy bias; the hands only includes hands that are double-dummy down; other hands that may be single-dummy down since declarer may not pick the diamond suit (made more likely since partner's possible diamond honor(s) are over dummy's) and we may require a spade lead to set up a quick trick that is needed to be cashed when partner comes in with a diamond (or any other) trick before disappearing on dummy's diamonds (or elsewhere). I don't suppose you could post up some hands where responder has a singleton diamond to analyse? I'd imagine it'd make a spade lead significantly worse than when dummy has a diamond suit. Another interesting re-analysis is for opener having 3-4♥ for the superaccept - I'd imagine many players/expert partnerships would allow superaccepts to have only 3 card support over 2NT then responder transferring over 2NT. If the 2♣ opener is allowed to have only 3 hearts, then the likelihood that a spade lead risks a spade trick evaporating into thin air decreases (eg less chance of declarer having doubleton spade AQ for example and increasing chance of AQJ where a spade lead won't blow a trick anyway). Quote Link to comment Share on other sites More sharing options...
OleBerg Posted March 7, 2010 Report Share Posted March 7, 2010 Ok I've analysed the hands 51-100 and I get 51 - opener cuebids... ... a diamond suit. Nice posts. They might even help jdeegan to "to gauge the quality of commentators." Quote Link to comment Share on other sites More sharing options...
jdonn Posted March 7, 2010 Report Share Posted March 7, 2010 I don't feel like analyzing 50 but the constraints still have problems. 2 responder doesn't have a slam try, slam is possible but you are short on values and can never get there accurately with xxxxx of trumps. 3 opener doesn't have a super-acceptance. 8 opener is too good to rebid 2NT. 11 opener doesn't have a super-acceptance. I stopped after 12 (but down the page on 34 I see responder with a spade void, huh?) Plus it's not like opener bids slam 100% of the time over the 5♦ bid, he has already shown 23-24 and responder isn't forcing to slam so doesn't he ever sign off? That seems to have not even been considered, as though 5♦ is a transfer to 6♥. Anyway it seems to me the only thing you are really close to proving is that a diamond is the best non-spade lead. Quote Link to comment Share on other sites More sharing options...
karlson Posted March 7, 2010 Report Share Posted March 7, 2010 Effervesce: So basically you think that 4♥ denies two fast losers in any other suit. Not sure I agree, but that's fine, we can include that. I also took out any east hands with a void. The rest of the hands, where you don't think north would bid 5d, seem to me to be judged quite subjectively. If you want to come up with some objective criteria, I'm happy to rerun it. But for now, more hands with your constraints here. Btw the reason that there were so many hands where opener had no diamond control is simply that in order to beat it, we need partner to have a trick somewhere, and usually that's in diamonds. He has a much better chance of having a trick there if opener has weak diamonds. Jdonn: You can always pick a few hands and say that you wouldn't have bid them this way and declare the whole exercise moot. I think some hands are probably a little too weak, and some a little too strong, but on average they are ok. What I don't see is any reason why any of this biases against a spade lead. What I've observed is that if you just keep making the south (or north) hand stronger, what goes up or down quite a bit is the chance of you being able to beat the hand at all, but the relative frequencies of the successful lead stay quite similar. What I also want to point out is that in all of the simulations, the probability of beating slam at all is quite low. We're only going to beat this if they've misjudged, or if the hands unfortunately don't fit well. So it's not particularly surprising that on the hands where slam is beatable at all, either opener or responder has somewhat marginal values. Btw, why is a diamond the best non-spade? Seems to me that a club is the big winer. Also, why can't responder have a spade void if 5d is natural? Quote Link to comment Share on other sites More sharing options...
jdeegan Posted March 8, 2010 Author Report Share Posted March 8, 2010 Nice posts. They might even help jdeegan to "to gauge the quality of commentators." :D :D :D It really has. One reponder wondered about the meaning of the 5♦ bid. I specifically stated that it was a Q bid showing the ♦A or KQ. Remember, south was Jimmy Cayne and north was Chuck or Susie Berger. Personally, despite my liking for old-fashioned bidding, I favor Q bidding the unsupported ♦K if it looks to be the best bid, but I certainly wouldn't do it sitting opposite JEC, and neither, I expect, would the burgers. I pays to know your opponents. The other issue I haven't heard mentioned is that more than 2/3 of the time a ♠ lead will give up either a trick (very often) or at least a tempo - and, you know this from the bidding - no simulations needed. When you start from that deep a hole, how good can a ♠ lead be? Just wait on your ♠ trick (you are behind the ♠A), and hope pard's 3-6 HCP turn into a trick. If declarer is missing the ♥Q with nine, he will normally misguess. Time now to crank up my ancient MS DOS copy of RPG and do my own simulations. :D :D :D Quote Link to comment Share on other sites More sharing options...
jdonn Posted March 8, 2010 Report Share Posted March 8, 2010 Jdonn: You can always pick a few hands and say that you wouldn't have bid them this way and declare the whole exercise moot. I think some hands are probably a little too weak, and some a little too strong, but on average they are ok.One point, it's a lot more than just a few hands. The person who analyzed them closely feels it is 59 of them. I would estimate I would have a problem with at least 40 of them. But I don't think the exercise is moot. I just think, with all due respect since you are doing something I'm not at all inclined to do, the conditions being run are simply not realistic. Second point it really means nothing to say on average they are ok. Just like you and I are 6'2 on average but that won't help either one of us in any endeavor where it's an advantage to be exactly 6'2. On top of that, it's the ones where either hand is too weak that are throwing it off in particular, if one hand is somehow too strong then there is probably no hope to set almost always. What I don't see is any reason why any of this biases against a spade lead. What I've observed is that if you just keep making the south (or north) hand stronger, what goes up or down quite a bit is the chance of you being able to beat the hand at all, but the relative frequencies of the successful lead stay quite similar.I can only give my general feeling, but if the opponents are on the strong side it's very important to lead aggressively so that you can set up and/or take your tricks before they vanish. If they are on the weak side it's very important to lead passively because they may have no hope to make except to be given a trick on lead. So that one or both hands are too weak in so many examples definitely biases against a spade lead, I feel. Btw, why is a diamond the best non-spade? Seems to me that a club is the big winer. Also, why can't responder have a spade void if 5d is natural?I may have misjudged on the diamond it was only a glance, it seemed to me to set most frequently leading through dummy's diamonds. And if 5♦ is natural and says nothing about black suit controls (in which case opener won't use them as the decision maker to bid slam) then ok, maybe we just have the AK of spades to take! Or the spade ace could even be in dummy then... Quote Link to comment Share on other sites More sharing options...
jdonn Posted March 8, 2010 Report Share Posted March 8, 2010 The other issue I haven't heard mentioned is that more than 2/3 of the time a ♠ lead will give up either a trick (very often) or at least a tempo - and, you know this from the bidding - no simulations needed. When you start from that deep a hole, how good can a ♠ lead be?It can still quite easily be best. It only matters if it gives up exactly the 12th trick, and if you can't get that trick back elsewhere. Your argument is like saying exercise isn't healthy because it dramatically increases your chances of a sprained ankle. Just wait on your ♠ trick (you are behind the ♠A), and hope pard's 3-6 HCP turn into a trick. If declarer is missing the ♥Q with nine, he will normally misguess.I like how the spade is just 100% to score if we don't lead it. As though opponents in 6♥ and lacking the king of spades and queen of hearts won't have a minor or two to throw any spade losers on. Quote Link to comment Share on other sites More sharing options...
karlson Posted March 8, 2010 Report Share Posted March 8, 2010 Effervesce: I did the stiff ♦ sim you asked for. Spade did better on this than on most other possibilities, but it was still about a 1-2.5 underdog.Hands. Jdonn: average was not a good word, I meant "most". I tried another sim with both opener and responder having much better hands (10hcp/7 losers for responder, 9 controls for opener), but I didn't find a single hand in 10k where 6 was beatable (lol). I think at this point, I've tried it with opener on the weaker side, and on the stronger side, opener without all controls, opener with all controls, responder on the weaker side and the stronger side, 5d as cue, as length, and as shortness, and through all of that, it's never been close. If there was some magical middle where a spade was clearly best, I think we would have seen at least part of the effect somewhere. Anyway, since no one else seems to care anymore, I'm done with these for now (unless someone has a specific request I guess, since it's easy). Quote Link to comment Share on other sites More sharing options...
jdonn Posted March 8, 2010 Report Share Posted March 8, 2010 If there was some magical middle where a spade was clearly best, I think we would have seen at least part of the effect somewhere.Like this perhaps? That is, only 17 hands of the 50 qualify. Of the 17, 8 only a spade will beat it, 6 any non-spade, one only a club lead, 2 any lead. Quote Link to comment Share on other sites More sharing options...
jdeegan Posted March 10, 2010 Author Report Share Posted March 10, 2010 The other issue I haven't heard mentioned is that more than 2/3 of the time a ♠ lead will give up either a trick (very often) or at least a tempo - and, you know this from the bidding - no simulations needed. When you start from that deep a hole, how good can a ♠ lead be?It can still quite easily be best. It only matters if it gives up exactly the 12th trick, and if you can't get that trick back elsewhere. Your argument is like saying exercise isn't healthy because it dramatically increases your chances of a sprained ankle. Just wait on your ♠ trick (you are behind the ♠A), and hope pard's 3-6 HCP turn into a trick. If declarer is missing the ♥Q with nine, he will normally misguess.I like how the spade is just 100% to score if we don't lead it. As though opponents in 6♥ and lacking the king of spades and queen of hearts won't have a minor or two to throw any spade losers on.:( :D :D Your last statement addresses the whole point. When I started constructing hands for RHO where 3-4-2-4 distribution let two spades go on diamonds (remember, Cayne is very unlikely to open 2NT with two doubletons), I saw that this made LHO at most 2-2 in the black suits, so 6♥ makes even if pard has the ♠Q and a ♦ or ♥ trick whenever dummy gets a spade pitch on a club. Essentially, when we gamble on finding pard with ♠Q, we still don't win probably more than half the time. As far as waiting on the ♠K, if we don't make a ♠ trick, we probably aren't going to beat the hand anyway. :D :D :D Quote Link to comment Share on other sites More sharing options...
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