Povratnik

Group A Povratnik 26 : 12 tim_ucin Boards mlbridge 21 : 14 Povratnik Boards

Exactly! Thank you all :D

The very first question: How can I get the list of my friends?

Group C Povratnik 8 : 32 Stephen Tu Boards I finished all my matches and will have enough time to rest before Event 16 begins :)... Cheers!

Group C Povratnik 26 : 34 icycookie Boards Povratnik 13 : 36 diana_eva Boards

Thank you. So I have only tomorrow evening to finish the match against diana_eva. I planned to do it anyway, but if something unexpected prevents me, I hope my non-acceptance will not be treated as resignation...

Some technical questions: - I never dared to try, but... Can I play several boards, then log out and finish the match tomorrow? - If I start playing before expiration, but don't finish on time - what happens?

Group C Povratnik 30 : 13 barmar Boards

I just am. Still not fully active, but somehow managed to finish the match against heart76. You're the next. Group C Povratnik 25 : 19 heart76 Boards

Group C Crashing but very elegant victory for zupey. Believed I was winning and was hoping for a big difference. My hopes are fulfilled, but belief turned out to be wrong. Wherever I had good result, zupey had better... Povratnik 5 : 36 zupey Boards Sorry hearts76, but I am departing in less than two hours, I have to pack. We'll play in the next year...

Anouncement: I am traveling abroad, so I'll be unavailable for 7 to 10 days. I will have access to computer and internet, but I'll hardly have time or wish to play serious matches. Report about my activities so far: - I was challenged by nige1 and sfi. These matches are finished. - I challenged ye17, billyjef, xenoquatz and zupey. Three matches are finished. Match with zupey remaines to be finished, I'll do that in the next couple of hours. - I was also challenged by hearts76, but I am not going to accept that challenge, unless I'm ready to play the whole match immediately. hearts76, if you tomorrow find the match still unaccepted, you may well cancel it, since I'll be already on the road. In that case, you'll be the first player challenged by me in early January. Cheers!

Group C Povratnik 20 : 24 billyjef Boards

Oh, I didn't read carefully, because I recognized the board I have played... If East is missing 10♥, then it's an easy double dummy problem, but without knowing the distribution of heart honors, it's virtually impossible. If East has QTx, it's literally impossible...

IMHO, if you cash even two spades, you ruin everything; you may cash the king, but why would you? You need two small spades on the table. One to discard on the last club, one to return to hand after you cash the last diamond. So correct order is: clubs, diamonds, spades. What did you mean to discard on the last club? EDIT: I was too fast. Tou have to cash king spade, because East lead a spade :)

Yes, it is 100%, but it seems I'm not savvy enough to copy the board here... :embarrassed: I might succeed later... P.S. I didn't make 7NT, just 6N+1 P.P.S. This is the link. Let someone savvier than me post it.

@nige1 Sorry, you lost me at the very beginning. I don't understand that type of tournament. Against WHOM I can have win, tie or loss? If that's essentially the same as team match with MPs counting, then your math is unnecessary, Stephen's line is definitely better. Can you make corresponding arithmetic for standard pairs tournaments? @Stephen Tu Since I have to write a short message to nige1, I'll take an opportunity to write one to you, in the same post. If you're so insensitive to insults, then it's a no brainer to me. I have a very effective answer: If you turn out to be succesful in finding the flaws of my answer, but unsuccesful in finding the flaws of your statement, just report what have you found. I'll help you to find more. Please don't write about anything else in your very next post. Just your thoughts about your statement and my answer. EDIT: I am putting another message in this post @nullve You are trying to say that bridge inferences are more important than pure math? I agree, but in this board you can't find anything useful, so we have to rely on good, old math...

@Stephen Tu Stephen, you are VERY quick on trigger! There is no way you could read and assimilate such a big post in an hour, yet you immediately wrote a fairly long "answer". The result is very disappointing... Your post consists of 9 segments and virtually (literally?) each one has a flow. Most of them I can knock down without saying anything new, just by putting a quote from some of my previous posts... That's precisely my objection to most of your posts :). Of course, since I am using foreign language, my posts could be even worse. But I wasn't much active on this forum so far; so you can check all my posts and convince yourself that my posts are usually short and to the point... Unless I am writing to YOU. Generally, your posts are the hell of a mess. Specifically, when I am writing to you, I tend to fall in one and the same trap - I assume what are trying to say, instead of just asking you that. But my last post had to be that long, because I want to stop inefficient practice and correct procedural mistakes made by both of us. I wrote ALL that had to be written but, unfortunately, most of the content remained undigested by you. So we have a problem again... Well, you missed it, I hope not deliberately... The core of the argument is my claim that you're looking at the wrong side of proportion. I explained it in the last part of my post. You ignored it totally. A guide for reading my previous post: At the beginning of the post, I said: I continued to explain the reasons of my dissatisfaction. See a few quotes: And what have I got? More of the same. You're still giving lectures to those ones who overslept lower grades of elementary school. You still haven't made a relevant claim. You still haven't offered one single useful conclusion. The few productive parts of your post address third grade problems... Don't understand me wrongly - not reading carefully the post you criticize - is the sin we're both guilty of. But this time you crossed all boundaries. You pick a few sentences to quote and neglect to properly read even that tiny portion of text. Look at this: Huh? WTF frequency vs. points? Let's say there are 100 other pairs, all in 4s, all play for the drop. You win 100 MP when you are right, when LHO is void. You lose 100 MP when you are wrong, when LHO has stiff K. There is no "point advantage" when everyone is in the same contract. It's just pure frequencies. You're "correcting" me by saying in two sentences what I said in one! Yeah, I know, it was hidden in the middle. In sandwich between first and last sentence... There is a comment where the first your sentence is "I don't get this argument at all.". In the last sentemce you said I was wrong. How do you know I'm wrong if you don't get it? And this one really pissed me of: Huh? I thought I already stated this many times, fairly clearly. This is my claim:trying to drop west's stiff K yields more matchpoints than taking the safety play in the long run, if >= 89% of the relevant field is in 4S. Or in other words, "IF 89+% of the field is in 4S, you SHOULD play for the drop", but "if <89 % of the field is in 4s, the others being in contracts yielding plus scores < 620, you SHOULD play safe". Clear enough for you? I really don't get your complaints about my clarity or "may vs.should". Most everyone else on the thread understands what I meant. A proper answer HAS to contain a clear message: a) Yes, I AM claiming that cashing the ace is better line than safety play. OR b) No, I am NOT claiming that cashing the ace is better line than safety play. Not only you haven't given a proper answer, you completely ignored everything that was said in the quote you picked yourself. You could well choose some other piece of my text and glue your mumbo jumbo as an "answer". You're "claiming" that a player should always pick the line with greater mathematical expectancy. Really? That's an insult. You should better not answer at all then "answer" this way. I never gave you an excuse (not to mention a real cause) to talk to me like that. "I claim nothing. I am just making fun by discussing.", would be a disappointing, but honest answer. I would appreciate it. There are some productive parts in your post, but they can wait. Now I have to ask you a direct question. (With the hope that I'll get a direct answer.) Besides obvious generalities, the only thing you properly articulated was the claim that cashing the ace is legitimate line of play. Nobody disagreed. Have you ever (in this thread) been trying to prove (or at least claim) ANYTHING more than that? If the answer is affirmative, PLEASE be as precise and specific as you can. If the answer is negative, PLEASE say it explicitely. I BEG you - don't throw at me another pile of trivial generalities as a replacement for direct and honest answer. And finally, I'd appreciate if you don't answer immediately, but make at least a 24h delay... (Frankly, I am afraid of another mess) Thank you for your time

Group C Povratnik 35 : 10 ye17 Boards

It isn't offered as a possibility. Are there some code that I could enter and make a poll that isn't at the beginning of a thread?

Sorry, before I finished this post, a RL issue had forced me to abandon the works for the time being. It turned out to be good, though, since the longer time usually makes a shorter and nicer post :). This post has to be big and ugly, but if there wasn't a sufficiently long pause, it would be MONSTROUS! God, if I was practical enough to just ask you that, a lot of yours and my time and effort would be saved... OK, I'll give you what you're asking for, but I would really like to shorten yours and my further posts, so I'll try to crystallize the things on global level first. It's by far more important than petty mistakes. About the process, for Stephen Tu exclusively. Of course, others also can read, but can and will be heavily bored... Your second mistake (a MAJOR one) You aren't splitting the questions "MAY I" and "SHOULD I". You MAY choose a certain line of play if it's reasonably good; if it has similar mathematical expectation as other lines. You SHOULD choose a certain line of play if it's clearly the best; if it has the greatest mathematical expectation or is clearly the best for some other needs that you consider important (it's the wisest, the most practical... or whatever). In this case you correctly estimated that, due to extraordinary high percentage of pairs who'll bid the same contract, you can afford to risk the game. There is no need to repeat your arguments, you did a proper job. Cashing the ace has about the same expectation as safety play, so you can play it. But SHOULD you? That's a new question, yet you're using the same old means. That means served you well with the old question (may I, could I), but are powerless with the new one (should I). Your writings mainly consist of general considerations and (far from correct) focusing of (wrong) parameters. That gave us satisfactory (over)proof that risking the game is legitimate choice, but I see nothing that could even moderately corroborate the new thesis - that cashing the ace is actually a better line. Using the common language, I'll just say: You're looking for answers at wrong place. THAT's your main mistake. All specific errors are just natural consequences of this one. So I'll not try to determine whether any of your deep convictions are wrong (they probably aren't). I'll concentrate on positive story that I have to tell - how these things really operate... * * * But first I need to introduce some terms. They aren't recognized in theory, I just coined them for this occasion. OUR group - The group of NSs who played the same contract as we did Local TOP, ZERO - The best/worst result in OUR group 800 group - The group of NSs who made better result than our best possible (4s+3) 300 group - The group of NSs who made better result than our worst possible (4s-1), but worse than 4s= BOTTOM group - The group of NSs who made worse result than our worst possible (4s-1) INNER group - The group that consists of OUR group and 300 group We can't reach 800 group under any circumstances. With any normal line of play, bottom group is also out of reach. So 300 is obviously the most important. More about that, later. * * * In your two large posts, there are four parts that I painted red, because (very) wrong conclusions could be implied from them. I'll cross over them, not necessarily in chronological order. Once again - whether you meant it wrongly, or were you just sloppy - isn't nearly as important, as positive story that I'm going to tell... I already partly commented this. Whatever my previous comment is missing, will be made up by my further story... It would be actually correct, if you could keep it totally isolated, "frozen in time and space". But you can't. You have a subtle feeling about the matter, but you neglected the rest of the picture. Continue to read, it will be clear... No, it doesn't. It can grow or shrink and neither is proportional to the number of people in the same contract.... Let's assume that every NS pair played the same contract. As it's already said - you have frequency advantage, I have points advantage. In this case, my advantage is clean ZERO. So your frequency advantage, no matter how small, literally guarantees you +EV. The severest case is a team match. Your f-ad works in its fullest, giving you the maximal 2.63 percentile points of +EV. Small, but relevant. Now, lets add the third table, making it a pair tournament. Now you can't beat me for 100%, because of sharing results. If you have clean TOP, I don't have ZERO, but 25%. If I have clean ZERO, you don't have TOP, but 75%. So whenever I'm wrong, you beat me for 75%. Your +EV is now 2.63%*75%=1.97%. Let's add the fourth table. Now you beat me for two thirds (formula is n/2(n-1), n is the number of tables where the board is played on). Your +EV is now 2.63%*2/3=1.75%. And so on... Your original example (ten tables) gives you +EV of 1.46%; 16 tables ~1.4%. So we can see that your advantage haven't grown, it shrank. And not proportionally, but fast in the beginning, then slower and slower. In the range typical for club tournaments (8-16 tables per board) it shrinks only a promil - from ~1.5% to ~1.4%. So what's the truth then? Does the number of people in the same contract work in my favor? No, it just pushes your EV toward the LIMES. I chose this particular case, because it's the only one simple enough to allow us comfortable monitoring; more complicated cases also have a limes, not necessarily the same. In this case limes is 1/76 = 1.316% (Exactly one tenth of original probability! I do believe it's only coincidence, but I'm not 210% sure. I need to check similar problem, with different probabilities...). So whenever your EV is above 1/76, it will fall in smaller and smaller steps down to 1/76, never reaching it. Whenever it's below 1/76, it will raise in smaller and smaller steps up to 1/76, never reaching it. So it works for me or for you, depending whether your current mathematical expectation is above or below the limes. Specific truth Exact number that serves as limes varies depending on parameters, but when number of pairs that plays the same contract grows - it invariably pushes your mathematical expectation toward the limes - whether it's good or bad for you. General truth Useful answers are elsewhere. You corrected yourself in the next post. Or at least I thought so... I reread your post (this time more carefully) and realized that this silly statement is offered as some kind of point after several entirely sound and correct paragraphs (in spirit, I didn't check the numbers). Until then, I presumed that it was correction of the blunder from previous post. So what did you try - to make a correction, to make a new statement, or both? If I take your statement literally, it's technically correct, but meaningless. My answer is: Yes, everybody's gains or loses depend on percentage of the field in every contract that was played in the board. So what? If I take it as correction of previous statement, I already told - it's better, but still not good enough. Let me continue my story and all will be revealed... In your original example, the board has been played on ten tables. Everybody bid 4s, but one pair faced successful sacrifice. Our group has impressive 90% of the field, but your EV is far from impressive - only +0.146%, TEN (!) times smaller than when it has 100% of the field. Lets drop the percentage once again, to see what's going to happen... Case A If we remove a pair that was in 300 group and add two pairs to bottom group and two pairs to 800 group, our group will have 9 of 13 or 69.23%. Your EV is now +0.98% - much BIGGER than with 90%... Case B This time we'll just add another three pairs to 300 group. Our group again has 9 of 13 or 69.23% of the field. But now, your EV is -2.52%... So with nearly 70% of the field, your EV could be +0.98%, but could also be -2.52%. What's wrong? The METHOD is deeply wrong. Save the few complete but limited examples that you gave us, you're trying to achieve something by analyzing our group in isolation. That's bound to failure. In this particular case, you're referring to size/percentage of our group (in the field) as if it's somehow possible to change it, without also changing the percentage of other groups. No wonder results are so erratic... Specific truth When the percentage of our group changes, the outcome depends on what happened to OTHER groups. General truth Useful answers are elsewhere. * * * As I already hinted - the key group is 300 group. The influence of all other parameters put together is practically negligible, in comparison with influence of the ROW NUMBER of pairs in 300 group. Yes, our mutual result depends on percentage of our group. But in INNER field, not in entire field. And even that is only theoretically. In practice, the only thing that really matters is - whether 300 group has 0, 1, 2 or MANY members. (MANY = 3, 4, 5...) We could say that row number of pairs in 300 group decides the ORDER of MAGNITUDE. Sizes of other groups in the field (including ours) decide only where we are in the same class of magnitude. In normal live tournaments, there are only four classes of magnitude - 0, 1, 2 and MANY. Lets say that p0, p1, p2 and p4 are their respective probabilities. If you're writing a book, you'd have to find the credible way to estimate and compare these probabilities. In practice, you can ignore p1 and p4. On bigger tournaments, you can also ignore p2. But you can never, ever forget about P0. Class 0 is bread and butter of your "collecting small profits" strategy. Lets return to the beginning. You just estimated that cashing the ace is legitimate line of play. Fine. You're done with phase 1 and can immediately play the move if you like it. We do play bridge primarily for enjoyment, after all. But if you have greater ambitions (want to judge whether this line is actually better), you're already in the phase 2. Now you should entirely change the perspective and take a view from the opposite side. Forget all obsolete arguments and immediately focus on the most essential question: What's the probability THAT NOBODY stopped in wrong contract AND NOBODY faced a successful sacrifice? Estimate p0 and if you're impressed - go for it! If you aren't - maybe you should just make the game your partner bid... How could you convince the audience that your decision is right? No idea, I don't think you can. But any sensible try has to be heavily leaned on your estimation of p0. Any other aproach is just mumbo jumbo... * * * If you remain biased in the favor of cashing the ace, I'm not worried. I know you're able to take care of yourself. I just feel sorry for many others who'll risk a good game not only when you do it, but also in many other cases when they clearly shouldn't... Disclaimers:

There is Golady convention. If the partnership is at least minimally developed, that convention alone should be sufficient, regardless of the rest of their system. On 1d South bids 2c (GF), N answers 3c (long diamond suit). There is a difference in comparison with usual sequence 1d-1h-2NT (or 3d). When hears 3d, North KNOWS the partner has at least an opening strength. So he quebids 3h. It could be only a NT control, but soon it will be revealed that it's actually a slam control. South will answer 4c, 4d or 4h - depending on specific meaning of these bids in their system. North will confirm slam interest by repeating 4h or bidding 4s. South knows that he has much more that he showed up so far and realizes that slam is a must and Grand is the real goal. He'll jump to RKCB bid (whatever it is in their partnership) and learn that partner has 3 aces. He'll ask for the only missing king and get a positive answer. Now... If North has any plus (any queen, 7th diamond, 3rd club), there are 13 tricks. If afraid to conclude 7NT, South can bid 7c. With 3rd club, North will say 7NT...

My God, I thought the deadline was Sunday (it usually is). Now I see it's actually Friday... Is there any chance? Whether the number is 31 or 33, it's odd. I could make it even...

On it! It does and it almost is. Yet the way it's written, it somewhat blurs the reality. Wait for my answer to him. Anyway, I mainly disagree with your post as a whole, but I wouldn't comment before I answer to Stephen, if there wasn't this blunder: Is this lapsus calami or what? The very existence of this group guarantees that I easily beat all who cash the Ace, even if they play only 4s!

@Stephen Tu Another misunderstanding :). When I said "I don't understand you", I had in mind the two red sentences only. I do understand the rest of your theory. If I wanted to express in one sentence all that I learned about your views, I'd say: Mathematical expectation is Alpha&Omega That's my perspective too, so all these misunderstandings are only temporary... Aaaaaah, now I understand why did you use the word "percentage". Though I still don't like the term "percentage advantage" the way you used it, it doesn't really matter. All that I wanted to ask - is answered by this one sentence. The rest of the post explains your general approach. It wasn't necessary, because I've been understanding it (and generally approved) from the very beginning. However, your long essay wasn't completely vain. It helped me to clearly see what's wrong in your set up. Please, don't understand me wrongly - you made an impression of a sound thinker and I mostly agree with you. I'm pretty sure, you'll choose the same line as me in vast majority of such cases. When we choose different lines (due to different tastes), they'll usually have the similar mathematical expectation. I don't discuss with you so intensive because I think YOU need my advice. I'm doing this because of many users who'll read your posts without understanding and harden themselves in wrong beliefs. To shorten this post, I'll cross over the rest very briefly: Paragraph No 2 I don't know whether to call the red part wrong, incorrect, or just wrongly set - but I certainly can't accept it as correct. It will be explained... Paragraphs No 3-7 They brought nothing new. Paragraph No 8 That's said less sloppily than in the previous post, but IMO, it's still below the passing bar. It will be explained... Paragraphs from No 9 to the end They cover your general approach, that I already perfectly understood. * * * So I owe you an explanation for painting some parts of your post in red. I'll do it in separate post. Just before that, I'd like to prevent remaining of any loose ends... Outside of red parts (in this and previous post), I don't see any source of potential disagreement between you and me. But I have to check that with you. Do you see anything else that needs a further discussion? If not, I'll write an essay of my own in the very next post.

This isn't correct. The percentage advantage of the overtrick grows proportional to the number of people in the same contract. As more people play the same, overtricks value goes up, the advantage of just being plus goes down. Here, the edge of the overtrick is rather small over the safety play, so you need > 80 percent in game. But if the edge were larger, e.g. a safety play to guard against a 4-1 break, rather than just playing for 3-2, the breakeven point would be much, much lower. If you are in habit of playing safe when in normal contracts your mp score will usually suffer. What isn't correct? I reread my statement and it's short, clear and entirely correct. And yet you somehow managed to misunderstand me. And I don't understand you (talking about the red part). When I say "percentage advantage of chasing an overtrick", I am talking about the frequency. The probability that LHO has a singleton king is greater than the probability that he has a void. The difference is about 2.63 percentile points. That's the advantage of chasing an overtrick that remains the same, regardless of the size or other attributes of the field. If you have in mind some other "percentage advantage of chasing an overtrick", unknown to me, please specify. I was talking about percentage advantage and points disadvantage of chasing the overtrick. You claim that my statement isn't correct and repeat my phrase, but with the word "chasing" removed. Now the question is - whether you're talking about the same thing (and the important word is missing, for any reasons) OR (more probably) you're trying to prove the incorrectness of my statement by talking about something else... The latter approach doesn't look entirely healthy, but I'll not be petty, I'll try to understand your statement. The percentage advantage of the overtrick grows proportional to the number of people in the same contract. If you wanted to say: The POINTS DISadvantage of (chasing) the overtrick SHRINKS proportional to the number of people in the same contract. That's plausible for discussion. If that's what you meant, we can continue. If you wanted to say: The percentage advantage ... grows ... in the sense of probabilities That's obvious nonsense, the field has no influence on probabilities of card distributions. If you wanted to say: Some OTHER percentage advantage ... grows ... You should first introduce the very existence of the thing you're talking about and THEN claim that "the thing" grows... If you wanted to say something entirely different, please specify. As more people play the same, overtricks value goes up, the advantage of just being plus goes down. Before I try to interpret this sentence, let me notice one small, but absolute flow: We weren't talking about "just being plus", we're talking about making a GOOD contract. In this particular case, 4s is the very best contract available to NS; 620 can't be bad and can be a great result (most of the time, it will be a VERY good result). Making 170 or 140 would be "just being plus"... Did you want to say - when more people play the same, the overtrick will get you a better result? If so: - The whole setup is wrong (I don't elaborate, because it's far from certain that I'm correctly guessing your claim) - Specifically, if you watch that parameter alone (the number of pairs playing the same contract), overtricks value (if we're talking about the result) doesn't go UP, it goes DOWN. You're more than qualified to check that... * * * I could (and perhaps should) just say "I don't understand you", instead of writing 900 hundred miles long post, but I didn't want to be perceived as arrogant. I hope you'll be less obscure next time... Apologies to everybody, for low efficiency.