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Thread: What constitutes "Perfect Play"?

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    What constitutes "Perfect Play"?

    I didn't know whether to hijack Tarzan's thread or to create a new one. So, without risking injury on my part, (nor to sabotage the Ape Man's thread itself), I shall ask here.

    While there seems to be some recent discussion about this idea of "Perfect Play", it got me wondering what the hell is PP? How would one go about curating a system for Combo PP? What will this allow for us a players at the table?

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    knowing the exact composition of the remaining cards ?

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    My interpretation of perfect play is how a computer could play ,this would be used as a benchmark, to see what is theoretically possible, but of course not humanly possible.

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    Quote Originally Posted by AndretheGiant View Post
    My interpretation of perfect play is how a computer could play ,this would be used as a benchmark, to see what is theoretically possible, but of course not humanly possible.
    Yeah, like splitting 3's v 9 in a positive count with an 8 and 10 surplus, looking for the double, of course.

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    So, perfect play would allow me to double T, 7 vs 8, with a surplus of 3's and 4's in this case?

    What would EV look like to the CPP player? Assuming flat betting?

    And...how would one go about simming this PP concept? I take it Farmer, Schlesinger, Gron, et al. have the answer to that?

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    Quote Originally Posted by dogman_1234 View Post
    So, perfect play would allow me to double T, 7 vs 8, with a surplus of 3's and 4's in this case?

    What would EV look like to the CPP player? Assuming flat betting?

    And...how would one go about simming this PP concept? I take it Farmer, Schlesinger, Gron, et al. have the answer to that?
    Is it not bad enough that there are now, what, THREE separate threads on this same topic, all asking the same questions? This forum is becoming intolerable.

    Don

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    Random number herder Norm's Avatar
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    Actually, it's a good question. Although the answers given are "correct" as they fit the definition; "perfect play" isn't really quite perfect. For example, perfect play does not take into account a situation where not splitting with a close call will get you an additional round with a favorable shoe.
    "I don't think outside the box; I think of what I can do with the box." - Henri Matisse

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    Quote Originally Posted by Norm View Post
    Actually, it's a good question. Although the answers given are "correct" as they fit the definition; "perfect play" isn't really quite perfect. For example, perfect play does not take into account a situation where not splitting with a close call will get you an additional round with a favorable shoe.
    I agree that it's a good question. In my recent posts of analysis results, although I have tried to be precise in at least the up-front description of strategy assumptions, I have also admittedly used the more vague and hand-wavy terms "optimal" and "perfect" in casual discussion, particularly where the details of the strategy were not the main point of discussion. Norm has pointed this out more than once, and I haven't done a good job of listening .

    I won't try to define either of those terms here. But it's maybe worth at least describing in more detail what a current best "computer player" looks like (i.e., the assumptions behind all of my analysis results), and pointing out some of the many ways that I am wrong when I describe that computer player as representing "optimal play."

    Norm's example is a good start: when determining the strategy for a particular round in the middle of a depleted shoe, the "horizon" stops at the end of that round. Not the end of the shoe, the end of the trip, etc. That is, for the purpose of evaluating any single round, the sole objective is maximizing the result of that round, as if the computer player planned to sit down, play that round, then get up and walk away. There is no consideration of, for example, making a "local" strategy decision that *hurts* expected return for that round, in exchange for improved "global" long-term performance of the shoe/trip/etc.

    (However, although *playing* strategy is "local," we can still evaluate and optimize *betting* strategy with a "global" perspective, as discussed in posts of recent analysis results.)

    Furthermore, that single-round playing strategy is not risk-averse. That is, by "maximizing the result of that round," I mean that the computer player's sole objective is to maximize the expected value of the overall outcome of the round, without consideration of variance.

    (Again, however, although single-round *playing* strategy is not risk-averse, the *betting* strategy does account for variance/distribution of round outcomes to limit risk, also as discussed in recent analysis.)

    Actually, I just said that the computer player's objective is to maximize expected return for a single round; this isn't quite true. Splitting pairs is complicated: if you split 2s vs. dealer 6, and draw a 10 to the first half of the split, it may be optimal to stand... but subsequently drawing another 10 to the second half, it may *now* be optimal to hit. This is the "Z" in "CDZ-" (composition-dependent zero-memory) strategy; we confine our possible *specification* of playing strategy to depend only on the dealer up card and the cards in the player's *current* (possibly post-split) hand. Sticking to zero-memory allows significant speedup in calculation of expected returns/variances, without sacrificing accuracy (i.e., it's still exact).

    But it's even worse. Even constrained to zero-memory playing strategy, the computer player still doesn't necessarily realize the *best* such strategy: that is, the computed strategy may yield an overall expected return that is slightly less than the best possible expected return among all possible zero-memory (and composition-dependent) strategies. This is the minus sign in "CDZ-": CDZ represents truly EV-maximizing composition-dependent zero-memory strategy, but we can only efficiently compute CDZ-.

    For an explicit example of the issue, consider single deck S17 DAS, and you're dealt 2-6 vs. dealer 5. EV-maximizing strategy is to hit... unless you are encountering this hand after having split 2s, in which case you should double down. If we are constrained to zero-memory strategy, so that we must decide to *always* hit or *always* double down in this situation, which yields a better overall EV?

    CDZ- strategy always hits. That is, we compute "pre-split" strategy for all possible hands, then apply that same strategy to all *post-split* hands as well whenever we encounter them.

    (The good news is that this suboptimality CDZ-<CDZ is very rare, and when it happens, the resulting difference in EV is pretty small. I can track down examples if there is interest. Also, I should point out that we can actually compute and evaluate better strategies than CDZ-. My CA also allows some refinements, referred to as CDP1 and CDP, that allow separate pre- and post-split strategy. But if we want more than just EV, but also variance for betting analysis, currently only CDZ- is supported.)

  9. #9


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    Quote Originally Posted by moses View Post
    One of the things I think I learned from Don is "don't sweat the small stuff
    I'll stop sweating the small stuff - starting precisely 2:27.16 this afternoon.

  10. #10


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    Quote Originally Posted by moses View Post
    In a heads up game. Suppose you hit 13vs6 in a negative deck and win. However, the card you took out of the deck causes you to to lose the next hand. The increase or decrease to your bottom line is minimal. But the attention could be costly.

    So you can wait until 2.30. But don't let me hear you haven't bought Gold Bold by 2.31. Or it's the flying pretzel move for you.
    Boss, Zee act, Zee act. Works best heads up. Lots you can away with. As for Gold Bond, I have dry skin, and use various creams good for dryness, and oddly enough, itch.

    And no, don't use KY gel as a moisturizing lubricant.

  11. #11


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    Quote Originally Posted by Three View Post
    Perfect play is playing and betting using combinatorial analysis to make the best decision for the deck composition at the time of each decision. In other words, there could be no improvement on long term results over perfect play because its bets and plays are fully optimal.
    What are you saying is the playing decision. How about the bet size before cards are dealt ? Should we use combinatorial analysis to find the edge before cards are dealt and bet according to calculated edge and Kelly Criterion ? LOL

  12. #12


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    Quote Originally Posted by Three View Post
    What are you laughing about? That is what perfect playing BJ is. It's usefulness is to put an upper bound on what is possible to achieve. It isn't about using a computer when gambling. Whether on the internet or in a brick and mortar casino that is illegal.
    I am using perfect strategy(perfect playing decision and perfect betting size) to play online casino games in my country
    Last edited by James989; 12-17-2017 at 04:36 PM.

  13. #13


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    Quote Originally Posted by Three View Post
    I would be willing to bet you agreed to not use a computer when you set up your account. Remember that little box you had to click that said you have read and agree to these conditions in order to set up your account? If you had to do so, when they determine you are using a computer you will forfeit everything including your deposit.
    I start to play it since 28 months ago and still playing . . . .They can't prove it !

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