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#1
October 20th, 2011, 11:27 AM
 guitarhero Member Join Date: Oct 2011 Posts: 9
2 deck, perfect play blackjack

If you used computer simulations to make all the correct decisions in 2 deck blackjack (all the correct decisions would obviously be based on what's left in the shoe, because computers can keep track of 13 counts.. penetration almost all the way to the end of the second shoe every time. What kind of advantages would this computer simulation present? 54%? 55%?
#2
October 20th, 2011, 12:20 PM
 aslan Executive Member Join Date: Mar 2007 Location: Las Vegas, NV Posts: 8,683

Quote:
 Originally Posted by guitarhero If you used computer simulations to make all the correct decisions in 2 deck blackjack (all the correct decisions would obviously be based on what's left in the shoe, because computers can keep track of 13 counts.. penetration almost all the way to the end of the second shoe every time. What kind of advantages would this computer simulation present? 54%? 55%?
This is not a clear question to me. You said "2 deck blackjack," and later you said "second shoe." I am not aware of two-deck shoe games. Also, I don't follow what you mean by "computers can keep track of 13 counts." Of course they can. Do you mean "all thirteen card values?"

Imagine we were down to the last ten cards in the shoe and there were 6 high cards and 4 low cards remaining, your advantage would be quite high at the end. If there were 10 cards remaining and the computer knew that 6 were tens, and the low cards were 8, 6, 5, 3, it would be easy for the computer to calculate all the possible hands and the correct odds for each. You would have a 60% chance of catching a ten on your first card, and a 56% chance of catching another ten on your second card, for a 34% chance of making a twenty. Of course, the dealer has the same chance, plus the fact that the dealer may also make a perfect hand in two ways, ten/8/3 and ten/6/5, not that these are not also available to you.

Some cases would be way lopsided in your favor, such as when there are five aces and 5 tens remaining. Chances are you will not be unfortunate enough to split aces and receive hits of two aces. BTW, if you get two tens, and the dealer has a ten showing, it would be a good time to split tens, and keep splitting them until you no longer can, since only twenty-one can win that hand.

I have no idea what the simulation would show overall, but it should be pretty healthy.
#3
October 20th, 2011, 12:32 PM
 stopgambling Senior Member Join Date: May 2011 Location: north Posts: 117

Would like some advice on 2 deck games!I never heard of a book talking about 2 deck games in depth.Since playing decision is so important and it is only single deck that get all the attention .I think 2deck games sort of got stuck in the middle between sd and 6 decks.There is not a lot of info that help us to play the game.The playing decision of 16 vs 10 and 15 vs 10 ,3 card 16 vs 9 ,15 vs 9 are so important .Just relying on basic strategy does not seem to be enough even with the help of index play with hi lo (since thats what i use)How many 4,5 needs to be played out or not play out to change a decision of hit/stand? Would the "Theory of Blackjack" help me to make a few adjustment for my use with the understanding of E.O.R. for 4,5 maybe ??Is there a more accurate way of playing insurance rather than just using hi lo 's insurance index of 2.4 in 2 deck/,but without going to "ten count" or "VIP COUNT" for insurance. I am obviously quite confuse of what to do in 2 deck since there is not a lot of info on it!I better stop typing because i m more lost than i was originally!!!!
#4
October 21st, 2011, 12:43 AM
 zengrifter Executive Member Join Date: Nov 2005 Location: SoCal Posts: 10,532

Quote:
 Originally Posted by guitarhero If you used computer simulations to make all the correct decisions in 2 deck blackjack (all the correct decisions would obviously be based on what's left in the shoe, because computers can keep track of 13 counts.. penetration almost all the way to the end of the second shoe every time. What kind of advantages would this computer simulation present? 54%? 55%?
#5
October 21st, 2011, 10:38 AM
 aslan Executive Member Join Date: Mar 2007 Location: Las Vegas, NV Posts: 8,683

Quote:
 Originally Posted by zengrifter Less than 1 tenth that. Depending on your bet spread. zg
There you go, guitarhero; sounds like someone actually simmed it. As for the explanation, we'll have to wait for the math gurus to weigh in.
#6
October 24th, 2011, 03:04 PM
 ericfarmer Member Join Date: Jul 2011 Posts: 67

Quote:
 Originally Posted by guitarhero If you used computer simulations to make all the correct decisions in 2 deck blackjack (all the correct decisions would obviously be based on what's left in the shoe, because computers can keep track of 13 counts.. penetration almost all the way to the end of the second shoe every time. What kind of advantages would this computer simulation present? 54%? 55%?
Usually no more than 5-10%, but possibly as much as 25%. The attached plot shows the distribution of expected return (in % of initial wager) vs. penetration (in % of the 104 cards in the shoe), assuming CDZ- strategy with ridiculously optimistic rules: S17, DOA, SPL4, RSA, with surrender.

The plot is a combination of simulation and combinatorial analysis: the blue points result from simulation of heads-up play through 1000 shuffled shoes; each point is the expected return for a corresponding depleted shoe, assuming "perfect" play optimized for that depleted shoe. The red curves are 10, 20, 30, ..., 90th percentile curves of the blue points. So, for example, even at 80% penetration (only about 20 cards left), 90% of the time your EV is less than 9%.

Hope this helps,
Eric
Attached Images

#7
October 24th, 2011, 06:15 PM
 tthree Executive Member Join Date: Mar 2011 Posts: 2,277

Quote:
 Originally Posted by ericfarmer Usually no more than 5-10%, but possibly as much as 25%. The attached plot shows the distribution of expected return (in % of initial wager) vs. penetration (in % of the 104 cards in the shoe), assuming CDZ- strategy with ridiculously optimistic rules: S17, DOA, SPL4, RSA, with surrender. The plot is a combination of simulation and combinatorial analysis: the blue points result from simulation of heads-up play through 1000 shuffled shoes; each point is the expected return for a corresponding depleted shoe, assuming "perfect" play optimized for that depleted shoe. The red curves are 10, 20, 30, ..., 90th percentile curves of the blue points. So, for example, even at 80% penetration (only about 20 cards left), 90% of the time your EV is less than 9%. Hope this helps, Eric
I think he wanted almost 100% penetration. "Almost all the way to the end of the second shoe(deck is what I think he meant instead of shoe) every time".
#8
October 24th, 2011, 08:34 PM
 MountainMan Senior Member Join Date: Nov 2009 Posts: 117

Quote:
 Originally Posted by ericfarmer Usually no more than 5-10%, but possibly as much as 25%. The attached plot shows the distribution of expected return (in % of initial wager) vs. penetration (in % of the 104 cards in the shoe), assuming CDZ- strategy with ridiculously optimistic rules: S17, DOA, SPL4, RSA, with surrender. The plot is a combination of simulation and combinatorial analysis: the blue points result from simulation of heads-up play through 1000 shuffled shoes; each point is the expected return for a corresponding depleted shoe, assuming "perfect" play optimized for that depleted shoe. The red curves are 10, 20, 30, ..., 90th percentile curves of the blue points. So, for example, even at 80% penetration (only about 20 cards left), 90% of the time your EV is less than 9%. Hope this helps, Eric
What software was used to generate the grafic?
#9
October 25th, 2011, 07:42 AM
 ericfarmer Member Join Date: Jul 2011 Posts: 67

Quote:
 Originally Posted by MountainMan What software was used to generate the grafic?
The data were generated using my blackjack CA (see here: http://sites.google.com/site/erfarmer/), with a wrapper to automate the Monte Carlo trips through the 1000 shoes. I made the plot using Mathematica.
#10
October 25th, 2011, 03:00 PM
 zengrifter Executive Member Join Date: Nov 2005 Location: SoCal Posts: 10,532

Quote:
 Originally Posted by ericfarmer Usually no more than 5-10%, but possibly as much as 25%. The attached plot shows the distribution of expected return (in % of initial wager) vs. penetration (in % of the 104 cards in the shoe), assuming CDZ- strategy with ridiculously optimistic rules: S17, DOA, SPL4, RSA, with surrender. The plot is a combination of simulation and combinatorial analysis: the blue points result from simulation of heads-up play through 1000 shuffled shoes; each point is the expected return for a corresponding depleted shoe, assuming "perfect" play optimized for that depleted shoe. The red curves are 10, 20, 30, ..., 90th percentile curves of the blue points. So, for example, even at 80% penetration (only about 20 cards left), 90% of the time your EV is less than 9%.
Well, I stand corrected! zg

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