jamegumb Posted February 22, 2019 Report Share Posted February 22, 2019 This was from a Robot Reward I just completed: All vul, Dealer South Link here: http://tinyurl.com/yyofjbk7 Robot (N) S AQ43H AQT94D 4C K54 jamegumb (S) S 9H K83D AKQC AQJT82 Bidding (opps silent): 1C / 1H / 3C / 3S / 4H / 4NT / 5C / 5NT / 6D / 7H / P Perhaps I should have figured out the Robot had the Club King and bid 7NT. But it's a reward race, so I'm giving myself maybe 1-2 seconds per bid. I'd think the Robot should in theory be the captain, as I've described my hand. Lead is the Diamond 8. Robot wins in dummy, crosses to the Spade Ace, and leads the Heart 9 from hand. Low (Heart 5) from East. And the Robot runs the 9! Thankfully, it works this time (East had J5 in the suit) and we quickly rack up 2210. But what calculation possibly makes this happen? Please to explain. Thanks! Quote Link to comment Share on other sites More sharing options...
johnu Posted February 22, 2019 Report Share Posted February 22, 2019 Seems clear to me. Eight ever, nine never B-) Quote Link to comment Share on other sites More sharing options...
DaveRolyat Posted February 22, 2019 Report Share Posted February 22, 2019 Is it a safety play against a 5:0 trump split? At IMP you can afford it, but at MP giving a trick away could be costly. Quote Link to comment Share on other sites More sharing options...
pescetom Posted February 22, 2019 Report Share Posted February 22, 2019 Are we going to miss such spectacular plays when we get Argine? Quote Link to comment Share on other sites More sharing options...
jamegumb Posted February 22, 2019 Author Report Share Posted February 22, 2019 Is it a safety play against a 5:0 trump split? At IMP you can afford it, but at MP giving a trick away could be costly. Maybe this is what it was "thinking"? But, of course, this is total points, so all that matters is making the contract. Yes, this does allow the Robot to pick up 5-0 Hearts with East. So it's seemingly a pretty perfect 50% chance. Though playing low to the King allows for picking up all 3-2 splits, 4-1 onside, 5-0 onside, and 4-1 offside with the Jack dropping. Or 68.7+14.15+1.95+2.83 = 87.63% if I'm doing the math properly. (Actually a little less, because you risk a club ruff crossing to dummy for a finesse on the 4-1 or 5-0 onside splits.) Quote Link to comment Share on other sites More sharing options...
HardVector Posted February 22, 2019 Report Share Posted February 22, 2019 Is it a safety play against a 5:0 trump split? At IMP you can afford it, but at MP giving a trick away could be costly.There is no safety play in a grand slam. Quote Link to comment Share on other sites More sharing options...
Stephen Tu Posted February 22, 2019 Report Share Posted February 22, 2019 Maybe this is what it was "thinking"? Presumably it's a bug or fluke in the deal sample generating algorithm running at very high speed/low resources generating a very tiny sample, not big enough to consistently reflect true probabilities, that happened to contain more 0-5 / 1-4 splits with the jack with East than deals with the J with West? Quote Link to comment Share on other sites More sharing options...
jamegumb Posted February 22, 2019 Author Report Share Posted February 22, 2019 Presumably it's a bug or fluke in the deal sample generating algorithm running at very high speed/low resources generating a very tiny sample, not big enough to consistently reflect true probabilities, that happened to contain more 0-5 / 1-4 splits with the jack with East than deals with the J with West? This (sample generating algorithm) also makes sense, but surely it couldn't be more than a handful of samples before the odds overwhelmingly favor playing for the drop. Unless I'm missing some tipoff the robot derived from the early play. Quote Link to comment Share on other sites More sharing options...
smerriman Posted February 22, 2019 Report Share Posted February 22, 2019 This (sample generating algorithm) also makes sense, but surely it couldn't be more than a handful of samples before the odds overwhelmingly favor playing for the drop.Given you know East doesn't have a void, I calculate: - a 13% chance you must finesse- a 52% chance you must not finesse- a 35% chance both options work If you simulate 10 hands under these conditions, about 5% of the time it will give the wrong conclusion.If you simulate 20 hands, it's about 1%. Nobody knows how many hands GIB simulates - but it's suspected to be quite small - while 1-5% is a low probability, it still means it will be making a glaring mistake like this 1 to 5 times every hundred deals (and those one in a hundred appear on the forum :) ) Quote Link to comment Share on other sites More sharing options...
jamegumb Posted February 22, 2019 Author Report Share Posted February 22, 2019 Given you know East doesn't have a void, I calculate: - a 13% chance you must finesse- a 52% chance you must not finesse- a 35% chance both options work If you simulate 10 hands under these conditions, about 5% of the time it will give the wrong conclusion.If you simulate 20 hands, it's about 1%. Nobody knows how many hands GIB simulates - but it's suspected to be quite small - while 1-5% is a low probability, it still means it will be making a glaring mistake like this 1 to 5 times every hundred deals (and those one in a hundred appear on the forum :) ) Appreciate the insight - what calculation did you do for the probability? My binomial calculator stops once the third variable (both options working) is introduced. Quote Link to comment Share on other sites More sharing options...
smerriman Posted February 22, 2019 Report Share Posted February 22, 2019 My programmer side beats my mathematical side hands down this time, I just ran a large number of tests of x simulations until the probability flatlined. Quote Link to comment Share on other sites More sharing options...
jamegumb Posted February 22, 2019 Author Report Share Posted February 22, 2019 My programmer side beats my mathematical side hands down this time, I just ran a large number of tests of x simulations until the probability flatlined. Fair enough. Thanks. Quote Link to comment Share on other sites More sharing options...
johnu Posted February 22, 2019 Report Share Posted February 22, 2019 My programmer side beats my mathematical side hands down this time, I just ran a large number of tests of x simulations until the probability flatlined. You can use Pavlicek's card combination calculator. If you assume East led a singleton diamond, a first round finesse is the percentage play, but I don't think that is a correct assumption. http://rpbridge.net/cgi-bin/xcc1.pl Quote Link to comment Share on other sites More sharing options...
smerriman Posted February 22, 2019 Report Share Posted February 22, 2019 We were referring to the probability a simulation would give the incorrect results, not the probability the finesse is the right play. Quote Link to comment Share on other sites More sharing options...
johnu Posted February 23, 2019 Report Share Posted February 23, 2019 We were referring to the probability a simulation would give the incorrect results, not the probability the finesse is the right play.You can run a billion simulations and it won't do you any good if your modeling assumptions aren't any good B-) Quote Link to comment Share on other sites More sharing options...
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