Doubling on 11 VS A

C

CasinoBlackjack

Member
I play perfect basic strategy when I play, but I still don't understand the logic or math behind some things.

First, why is an 11 against an Ace not a double down after the dealer has peeked? Is it because the hand is "soft", which allows the dealer more flexibility in drawing a hand?

Also, why is an A/2 and A/3 only a double down against 5/6 up where A/4 And A/5 are double downs against as little as a 4?
 
FLASH1296

FLASH1296

Well-Known Member
CasinoBlackjack said:
I play perfect basic strategy when I play, but I still don't understand the logic or math behind some things.

First, why is an 11 against an Ace not a double down after the dealer has peeked? Is it because the hand is "soft", which allows the dealer more flexibility in drawing a hand?

Also, why is an A/2 and A/3 only a double down against 5/6 up where A/4 And A/5 are double downs against as little as a 4?
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You mentioned "logic", by which you clearly mean figuring out your best play by "thinking it through".
If that was possible, then it would not have taken a century or so before Basic Strategy was correctly computed.

Basic Strategy is determined by simulating the hand in question and playing it out Billions of times.
The results are tabulated and the the best play is seen to be the one that wins the most money or loses the least money.

Ace vs. 11 has a different Basic Strategy depending on the numbers of decks and on whether or not the dealer hits Soft 17.
In a single deck game you Double, as you do in all H17 games.
Otherwise it is a basic strategy Hit.

The soft hands that you mentioned do not provide much profit. A-4 vs. a dealer's 4 is one of the closest plays in all of Blackjack. The actual closest play is A-2 vs. a dealer's 5. These plays are toss-ups and it does not matter how you play them. The "correct" play may win an extra one or two cents on a $10 wager.

Blackjack Attack, 3rd ed. by Don Shlesinger has extensive charts which will show you your percentage of win or loss for EVERY possible hand that you can be dealt.

 
S

SystemsTrader

Well-Known Member
Because the odds say you will make more money hitting instead of doubling that 11 v A. There is a point for counters where doubling will earn you more money. So hitting will give you an EV of .146106 and doubling will give you an EV of .118365. Now if you play a game where the dealer hits a soft 17 then this changes things. Now you have the edge to double over hitting and the EV changes to this. Hitting .105943 and doubling is .112521.

It's the same thing for the A/2 and A/3's the odds dictate how to advantageously play your hands.
 
EasyRhino

EasyRhino

Well-Known Member
CasinoBlackjack said:
First, why is an 11 against an Ace not a double down after the dealer has peeked?
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As noted, this is a close play. It IS basic strategy in an H17 game, and it's also the correct play in a high count.

But the reason it's close is because there's a significant chance the dealer will still draw out to a pat hand (and that you won't get a good total by drawing one card). The H17 rule , while generally disadvantageous, increases the dealer's chance of busting, which, somehow, shifts the math in favor of doubling.

Also, why is an A/2 and A/3 only a double down against 5/6 up where A/4 And A/5 are double downs against as little as a 4?
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You know, I don't understand this one at an intuitive level either. It seems just as difficult to improve A2 with one card as it does to improve A4 or A5.
 
G

GeorgeD

Well-Known Member
CasinoBlackjack said:
I play perfect basic strategy when I play, but I still don't understand the logic or math behind some things.

First, why is an 11 against an Ace not a double down after the dealer has peeked? Is it because the hand is "soft", which allows the dealer more flexibility in drawing a hand?

Also, why is an A/2 and A/3 only a double down against 5/6 up where A/4 And A/5 are double downs against as little as a 4?
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Like flash said it's not always what's logical but a matter of following simulations and the EV that's been calculated, but I understand you want to make it "feel right". I cringe doubling 11 VS 10 .. especially of I pull an Ace.

One thing to think of on the 11 Vs Ace (or any double) is that you reduce the chance of a win because you can only draw one card. What happens if you draw a 2 or 3 on that 11? You can hit again and maybe get a 6 or 7. Looking at a dealer A all you know is he doesn't have 21. Maybe there's an 8 or 9 under that ace or something that he draws a pat hand to.


On the A/2 A/3 I always figure I might draw a 3 or 4 and have to hit again. I think the chance of busting is too high vs the chance you will draw a good pat hand. While if you see a dealer 5 or 6, HIS chance of busting is high, so it's worth the risk of doubling ... even of you pull a 15 hopefully the dealer will bust.



One way to thoi
 
moo321

moo321

Well-Known Member
The A2 thing is based on having the option to re-hit if you draw another low card.
 
F

fredperson

Active Member
double 11 vs A

Many years ago, I ran simulations of a few million hands and discovered that the proper play was to double 11 vs dealer ace. The number of decks, and
h/s17 made no difference. As a matter of fact, the EV of double 11 vs A was slightly better than double 11 vs 10
I suspect the reason many "experts" suggest otherwise is due to a simple "bug" in the "simulations" or the "mathematical analysis". I won't go into that here, but it would explain the discrepancy.
 
moo321

moo321

Well-Known Member
fredperson said:
Many years ago, I ran simulations of a few million hands and discovered that the proper play was to double 11 vs dealer ace. The number of decks, and
h/s17 made no difference. As a matter of fact, the EV of double 11 vs A was slightly better than double 11 vs 10
I suspect the reason many "experts" suggest otherwise is due to a simple "bug" in the "simulations" or the "mathematical analysis". I won't go into that here, but it would explain the discrepancy.
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I doubt it. Run a few billion hands and see if it still comes out that way.
 
C

callipygian

Well-Known Member
fredperson said:
I suspect the reason many "experts" suggest otherwise is due to a simple "bug" in the "simulations" or the "mathematical analysis". I won't go into that here, but it would explain the discrepancy.
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Occam's Razor suggests your simulation, not the hundreds of others which agree, is the erroneous one.

But let's put this to the ultimate test - instead of glibly saying how you "won't go into that here" and insist you're correct, why don't you go into that here and prove to us that you are?
 
FLASH1296

FLASH1296

Well-Known Member
Callipygian is quite correct.
A fundamental tenet of empiricism is that, lacking sufficient data,
(and you have revealed nothing), "Occam's Razor" does indeed apply.

Your claim establishes the "null hypothesis" in this case.

Incidentally, what was your standard error ?

I prefer a sample size getting it down to below .02 Don't you ?

The source of your patently egregious error is probably that your sample size is insufficient.

An hour ago I was checking out the Standard Deviation and R.O.R. for a particular set of game conditions. I just picked up a copy of John Auston's "World's Greatest Blackjack Simulation" The book contains the results of more than 800 Billion simulated hands. Not 800 Million, and not a "few million" as you said.

Hint: I am trying hard to give you a face-saving device here. Take it. I do not actually believe that sampling size is at fault because while your statement re: doubling 11 vs. Ace is clearly wrong, your "finding" of doubling 11 vs. Ten having less positive equity than the former is ludicrous.

The reader is referred to the precise equity figures as compiled and exhaustively tabulatd in "Blackjack Attack, 3rd ed.


"
" ...there is a method to scientific thinking and it includes being constantly vigilant
against self-deception and being careful not to rely upon insight or intuition in place of
rigorous and precise empirical testing of theoretical and causal claims."
 
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K

Kasi

Well-Known Member
FLASH1296 said:
Ace vs. 11 has a different Basic Strategy depending on the numbers of decks and on whether or not the dealer hits Soft 17.
In a single deck game you Double, as you do in all H17 games.
Otherwise it is a basic strategy Hit.
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11 vs Ace is also a BS double in a 2D S17 game.
 
F

fredperson

Active Member
doubling 11 vs ace

callipygian said:
Occam's Razor suggests your simulation, not the hundreds of others which agree, is the erroneous one.

But let's put this to the ultimate test - instead of glibly saying how you "won't go into that here" and insist you're correct, why don't you go into that here and prove to us that you are?
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I'm sorry if I offended you people with my post on this topic. Let me explain a little more....

First of all, I think we all know that the development of basic stratgey was not dependent on computer simulations, but rather on mathematical analysis.
As a matter of fact when I wrote a BJ simulator in 1979 I started with the basic strategy in Thorpe's Beat The Dealer which was not the product of simulations. Since I was running on a Radio Shack Model III computer with a Z80 processor, a million simulations took about a week, so running a billion simulations was out of the question. However having a degree in statistics I was able to determine an acceptable level of correlation from a million hands which suited my objectives.

The whole purpose of my work was to develop and evaluate a progressive betting system, which I have been using ever since. The simulations did produce reams of statistical data, from which I incidentally derived the double 11 vs ace exception to BS.

I have not kept any kind of data on the value of this change in actual play, but empirically I know it is valid, at least in the context of the way I play BJ.
 
moo321

moo321

Well-Known Member
fredperson said:
I have not kept any kind of data on the value of this change in actual play, but empirically I know it is valid, at least in the context of the way I play BJ.
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Well, have fun with that.
 
Tarzan

Tarzan

Banned
Instances to double down 11 against dealer ace up

Depending on what is going on with my "mood ring" and my psychic energy flow and if I chanted the right mantras recommended by Zengrifter----I will always double down the 11 against the Ace if the true count is 3 or better. The "illustrious 18" note to do it at TC1 or better but I like a little more reassurance! Outside of that instance I always just hit it. Safe basuc strategy play is to just hit it as a dealer ace up leaves a lot of possibilities to make a hand.
 
Katweezel

Katweezel

Well-Known Member
Oh Yeah, double 11 V A!

Tarzan said:
Depending on what is going on with my "mood ring" and my psychic energy flow and if I chanted the right mantras recommended by Zengrifter----I will always double down the 11 against the Ace if the true count is 3 or better. The "illustrious 18" note to do it at TC1 or better but I like a little more reassurance! Outside of that instance I always just hit it. Safe basuc strategy play is to just hit it as a dealer ace up leaves a lot of possibilities to make a hand.
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Doubling 11 V A is my favorite play - when TC1 or better - and I love it! Especially at my favorite casino where you get your double back if she makes her BJ. (ENHC)

I'm also in love with the low 30.76% probability of her scoring a BJ! (16/52) Which makes me an almost 70% favorite for her NOT to get a BJ. Even if she does, I get my DD back. The more I did it, the less fear and the more confidence. Now, it's on automatic.:cat:
 
sagefr0g

sagefr0g

Well-Known Member
Katweezel said:
.. The more I did it, the less fear and the more confidence. Now, it's on automatic.:cat:
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lmao, this reminds me of upon just learning the I18, the first time i doubled A8vs6. lol, i was shaking like a leaf and won the hand.:cat::whip:
 
S

StudiodeKadent

Well-Known Member
Katweezel said:
Doubling 11 V A is my favorite play - when TC1 or better - and I love it! Especially at my favorite casino where you get your double back if she makes her BJ.
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I gamble at the Wynn Macau usually, so I agree with you. Its Original Bets Only if dealer BJ's, and the odds are definately in favor of doubling down on all 11's.
 
K

Kasi

Well-Known Member
StudiodeKadent said:
I gamble at the Wynn Macau usually, so I agree with you. Its Original Bets Only if dealer BJ's, and the odds are definately in favor of doubling down on all 11's.
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Here are my questions.

If DAS is allowed, and, say, you split, 8,8 vs A, bust on the first split hand but get 8,3 on the second hand and double it, is the first busted hand removed before the dealer checks for BJ?

You want to double 11 vs Ace if original bet returned, it's no different than if the dealer checked for BJ first? Maybe if you don't include DAS?

If you include only doing that if counting, maybe fine. If BS only, I wouldn't double all 11's vs Ace.

Well, you know, if I ever actually had to worry about it, which i don't. lol.

The only ENHC games I've played were on the internet and none of them were OBBO or BB+1 games so I'm just asking lol.
 
S

StudiodeKadent

Well-Known Member
Kasi said:
Here are my questions.

If DAS is allowed, and, say, you split, 8,8 vs A, bust on the first split hand but get 8,3 on the second hand and double it, is the first busted hand removed before the dealer checks for BJ?
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At the Wynn Macau your hand is immediately removed when you bust. You don't get busted bets back against a dealer BJ, however all doubling and splitting wagers are returned.

The dealer doesn't check for Blackjack (i.e. hole card), the dealer just draws his/her hand.

You want to double 11 vs Ace if original bet returned, it's no different than if the dealer checked for BJ first? Maybe if you don't include DAS?
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I'm using the basic strategy from http://www.wizardofmacau.com, the Galaxy basic strategy (since the Wynn strategy assumes 4 decks when the Wynn changed to 6 decks a year ago). That strategy (which works at the Cotai Strip, the Galaxy casinos and (now) the Wynn) says to always split on aces and eights.
 
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