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Thread: Doubling 10 vs 10

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    Doubling 10 vs 10

    I know the index for doubling 10 vs 10 is +4, and I think the risk adverse index is +7. My question is at what count is this play positive EV?

    It’s my understanding that the index number to double is when the EV is greater for doubling than just hitting. I think this means I could still have a positive EV at a lower index number. I guess what I’m asking is do I still have positive EV on doubling 10 vs 10 at a lower count than +4, like at +1 or +2?

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    Quote Originally Posted by Dbs6582 View Post
    I know the index for doubling 10 vs 10 is +4, and I think the risk adverse index is +7. My question is at what count is this play positive EV?

    It’s my understanding that the index number to double is when the EV is greater for doubling than just hitting. I think this means I could still have a positive EV at a lower index number. I guess what I’m asking is do I still have positive EV on doubling 10 vs 10 at a lower count than +4, like at +1 or +2?
    No. Like all indices a lower count indicates a negative expectation.

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    Quote Originally Posted by Dbs6582 View Post
    I think the risk adverse index is +7
    I'll save Don some work here - it's averse. No D.

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    Quote Originally Posted by 21forme View Post
    I'll save Don some work here - it's averse. No D.
    Thanks! Made me chuckle. I know the difference between averse and adverse. Typed that post early in the morning.

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    Quote Originally Posted by Dbs6582 View Post
    I know the index for doubling 10 vs 10 is +4, and I think the risk adverse index is +7. My question is at what count is this play positive EV?
    You are asking about an EV maximizing index. 10vT is the most important RA index. The play is pretty much based on ace density. Without an ace side count I wouldn't go there. The EoR of the ace is about twice the EoR of the T. The T is almost 50% higher magnitude than the low card group's average. The 7 EoR is about twice as much as the low card group and about 50% more than the magnitude of the T. EoRs (2-A):

    (-1.9307, +0.5811, +0.55844, +0.6370, +0.8799, +0.8810, +1.6360, +0.8464, -0.0494, -1.0164, -1.9307)
    Quote Originally Posted by Dbs6582 View Post
    It’s my understanding that the index number to double is when the EV is greater for doubling than just hitting
    That is the EV maximizing definition.
    Quote Originally Posted by Dbs6582 View Post
    I think this means I could still have a positive EV at a lower index number.
    Yes.
    Quote Originally Posted by Dbs6582 View Post
    I guess what I’m asking is do I still have positive EV on doubling 10 vs 10 at a lower count than +4, like at +1 or +2?
    We would need to know your count system to answer this, but 10vT is by far the most important RA index. I wouldn't double without strong ace information. Add 7 info to that and the index becomes much stronger.

    Here is a link to a Hilo EV chart for 10vT. Just pick your rules and 10vX:

    https://www.card-counting.com/cvcxonlineviewer3.htm

    The high adjustment for RA play says at the lower EV maximizing index you will be making a lot of actual negative EV doubles due to poor correlation of the count to the play. Either gather better info to fix the correlation of info used to make the call, or use the RA index, or be prepared for a wild ride for small gain in EV between the EV maximizing index and the RA index.
    Last edited by Three; 05-24-2018 at 06:58 AM.

  6. #6


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    Quote Originally Posted by Three View Post
    You are asking about an EV maximizing index. 10vT is the most important RA index. The play is pretty much based on ace density. Without an ace side count I wouldn't go there. The EoR of the ace is about twice the EoR of the T. The T is almost 50% higher magnitude than the low card group's average. The 7 EoR is about twice as much as the low card group and about 50% more than the magnitude of the T. EoRs (2-A):

    (-1.9307, +0.5811, +0.55844, +0.6370, +0.8799, +0.8810, +1.6360, +0.8464, -0.0494, -1.0164, -1.9307)

    That is the EV maximizing definition.

    Yes.

    We would need to know your count system to answer this, but 10vT is by far the most important RA index. I wouldn't double without strong ace information. Add 7 info to that and the index becomes much stronger.

    Here is a link to a Hilo EV chart for 10vT. Just pick your rules and 10vX:

    https://www.card-counting.com/cvcxonlineviewer3.htm

    The high adjustment for RA play says at the lower EV maximizing index you will be making a lot of actual negative EV doubles due to poor correlation of the count to the play. Either gather better info to fix the correlation of info used to make the call, or use the RA index, or be prepared for a wild ride for small gain in EV between the EV maximizing index and the RA index.
    Thanks Three! Wow, this is exactly what I was looking for. The attached link was very helpful. Using my counting system (hi lo), it looks like this starts being a positive EV play at 0 and above.

    The reason I started thinking about this is because of Ian Anderson’s “Ultimate Gambit”. This came up on another forum so I went back and reread Ian’s chapter on the “Ultimate Gambit”. As I’m sure you know, one of his plays is to double 10 vs 10 all the time. It got me wondering when this play becomes negative EV. I’m not looking at incorporating the “Ultimate Gambit” into my play. It’s just something that was on my mind. Your answer was perfect! And I do sometimes keep a side count of aces with hi lo. It makes sense that this info helps with this play. Thanks again!

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    Quote Originally Posted by Dbs6582 View Post
    Thanks Three! Wow, this is exactly what I was looking for. The attached link was very helpful. Using my counting system (hi lo), it looks like this starts being a positive EV play at 0 and above.
    It is negative EV below TC +4 because at that point you are doubling your money at risk to win less money, in the long run, than you would have if you didn't double your risk. What you have to realize is "The Ultimate Gambit" was for a different age. Back then you had a ton of EV to gain and he was trying to get away with a much bigger spread than he would have otherwise been able to use. You would do well to forget about the stupid things he did to look stupid and try to find things to look stupid that aren't so stupid.

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    Quote Originally Posted by Three View Post
    It is negative EV below TC +4 because at that point you are doubling your money at risk to win less money, in the long run, than you would have if you didn't double your risk. What you have to realize is "The Ultimate Gambit" was for a different age. Back then you had a ton of EV to gain and he was trying to get away with a much bigger spread than he would have otherwise been able to use. You would do well to forget about the stupid things he did to look stupid and try to find things to look stupid that aren't so stupid.
    You keep misreading the OP's question. He isn't asking when the e.v. for doubling T vs. T exceeds the e.v. of hitting. He's asking when doubling has ANY positive e.v. Period. Do you understand the difference? if you double a small positive e.v., it might turn out to be lower than the hitting e.v., so you don't double. But the e.v. is still positive!

    Don

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    Quote Originally Posted by DSchles View Post
    You keep misreading the OP's question. He isn't asking when the e.v. for doubling T vs. T exceeds the e.v. of hitting. He's asking when doubling has ANY positive e.v. Period
    You need to reread my response that you quoted. I addressed exactly that. Why do you think I called it stupid? I gave him the info he needed in the link in a previous post. Then I cautioned him on the idea he was considering and gave him the reason why.

    You can encourage him to follow a massive BR strategy of yore with his confessed small BR by answering his question and letting him do something stupid with the answer, but I am going to give him the facts, pro and con, and let him decide. The fact is the strategy he is thinking about was for a different time and a massive BR, neither of which apply to him.

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    Quote Originally Posted by Three View Post
    You need to reread my response that you quoted. I addressed exactly that. Why do you think I called it stupid? I gave him the info he needed in the link in a previous post. Then I cautioned him on the idea he was considering and gave him the reason why.

    You can encourage him to follow a massive BR strategy of yore with his confessed small BR by answering his question and letting him do something stupid with the answer, but I am going to give him the facts, pro and con, and let him decide. The fact is the strategy he is thinking about was for a different time and a massive BR, neither of which apply to him.
    Three, the first answer you gave me was perfect! Since Don is much better with the English language than me, he clairified my question. Don understood exactly what I was asking. Thank you!

    Based on the game I’m playing and using hi lo, your link indicates I start having a positive expectation at about +0.5 for this play (double 10 vs 10). This does not mean I will do this, meaning double my 10 vs 10 at a +1 count.

    Along with wanting to understand the “Ultimate Gambit” better, there was another motive for my question. It’s the opposite of the risk averse concept. My bankroll is pretty much unlimited for the stakes I play so I don’t think in terms of bankroll or ROR. I’m just trying to generate as much EV as possible...and I also like playing aggressively. Therefore, I try to double 10 vs 10 and 10 vs 11 when I’m at a +4. I wanted to know what happened if I was slightly off with the count and happened to double the 10 vs 10 on a +3 count. It looks like that’s still a positive EV play, just not as positive as if I had hit that hand. I get why I that’s the case, and I’m comfortable living with the consequences.

    Both your and Don’s posts have been very helpful. Thank you!!!

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    While RoR may not be a concern to you, the certainty of BR growth should be. That involves factoring risk into your play. Having the attitude shown in this thread will have your results far more random on the way to the long run that is much further into your future than if control risk. See SCORE and n0 (n-zero). These stats tell you the strength of your AP play and how long it will take before you are no longer gambling. If you are okay with gambling for a far longer time before you are likely to be ahead then that is your decision. Just understand that is the decision that you are facing. It isn't I can afford to give up some EV. It is how long do I want my results to be random before EV overcomes SD. By increasing variance (SD^2) while decreasing EV you are working the equations for SCORE and n0 in the wrong direction in both the numerator and the denominator. If your thread stating casinos don't back of enough APs is any indication, you have no need to trash the SCORE, n0, and CE.

  12. #12


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    Quote Originally Posted by Three View Post
    While RoR may not be a concern to you, the certainty of BR growth should be. That involves factoring risk into your play. Having the attitude shown in this thread will have your results far more random on the way to the long run that is much further into your future than if control risk. See SCORE and n0 (n-zero). These stats tell you the strength of your AP play and how long it will take before you are no longer gambling. If you are okay with gambling for a far longer time before you are likely to be ahead then that is your decision. Just understand that is the decision that you are facing. It isn't I can afford to give up some EV. It is how long do I want my results to be random before EV overcomes SD. By increasing variance (SD^2) while decreasing EV you are working the equations for SCORE and n0 in the wrong direction in both the numerator and the denominator. If your thread stating casinos don't back of enough APs is any indication, you have no need to trash the SCORE, n0, and CE.
    Understood! Point taken! The one comment I take issue with you is calling what I’m doing “gambling”. The way I’ve always viewed this word is more in the line of hoping to win in a negative EV situation. That is not what I am doing. Even if I decide to double a 10 vs 10 at a +3, this is still a positive EV situation. So by my definition of the word, this is NOT gambling.

    Do you see what Ian Anderson did as “gambling”? He made several plays like this in his “Ultimate Gambit”. What I’m considering doing is peanuts compared to what he did. He still saw himself as being an AP (and I do too). In fact, it’s my understanding that he was voted into the Blackjack Hall of Fame so it looks like many APs thought Ian was an AP. I’m sure Ian Anderson was interested in bankroll growth (just as I am) when he used his “Ultimate Gambit”. The math for this strategy is the same then as it is now.

    My reasons for my question are actually a little more complicated than what I’ve said, but suffice it to say you’ve given me the answer I needed. Thank you!
    Last edited by Dbs6582; 05-24-2018 at 11:19 AM. Reason: Misspelled word

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    Quote Originally Posted by Dbs6582 View Post
    Understood! Point taken! The one comment I take issue with you is calling what I’m doing “gambling”. The way I’ve always viewed this word is more in the line of hoping to win in a negative EV situation. That is not what I am doing.
    Let me put it this way. If you were to wait until TC +3 and make a bet and quick BJ for life after that bet would you be gambling? Would you be more likely to win that bet or lose it? What are the possible outcomes and their probabilities? How certain are you that you would be ahead when the bet is resolved? If you have an advantage but are more likely to be behind after you are through playing is that gambling?

    Quote Originally Posted by Dbs6582 View Post
    Do you see what Ian Anderson did as “gambling”?
    What we do is about the long run. After enough cycles through your n0 you should be ahead. A huge spread will lower n0 so he could play through it many times. His Gambit was to get away with things he couldn't otherwise get away with that more than made up for what he gave up. Some don't think he actually accomplished that. Understand the whole picture not parts of it. Your job is to look stupid without being stupid and look like you are essentially gambling when you have calculated everything to make sure you still have a high SCORE, aka a low n0.

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