Blackjack Switch Basic Strategy Research

#1
Two basic strategies for this game can be found on Arnold Snyder's Blackjack Forum Online site:
http://www.blackjackforumonline.com/content/blackjackswitchbasicstrategy.htm

And another one by "The Wizard of Odds" Mike Shackleford can be found here:
http://wizardofodds.com/blackjackswitch

Both differ from standard H17 strategy, and there are minor disagreements between the two. Time to monkey around with it.

The reason BJ Switch strategy differs from standard BS is the push-on-dealer-22 rule. It's hard to visualize how this would make a difference, but apparently it does. So I used my CVData simulator to find an ideal basic strategy.

Methodology:

First, I programmed the push-on-22 rule into a CVData sim, by calling it a negative bonus, where if the player doesn't bust and the dealer busts with 22, the player pays his win back to the house. What an ugly rule! Then I applied the brute-force method of deducing plays. It works like this- you start with the hit-or-stand 16 plays, have two players playing agains the dealer, with the only difference being one always hits on 16, and one always stands on 16. By subtracting the resulting win rates for each player on the 16 plays, you can determine against what dealer upcard it is better to hit or to stand. Then you run another sim for the 15's and the 14's, down to the 12's. This is arduous but necessary.

Once you have the correct basic strategy for hit-or-stand, you do the same thing with the hard and soft doubles. You can do these all at once, just one sim. Finally, you run another sim for the splits. At this point you have enough information to provide a complete basic strategy for the game.

Note: these results do not take into account the benefit of switching! That's a whole different topic, but it should be independent of the way you play each hand after you have switched, which is the purpose of a basic strategy. I ran a sim comparing the Monkey Basic Strategy vs. the Bishop Basic Strategy, the Wizard Basic Strategy, and standard H17 multideck Basic Strategy.

Here are the results:
Code:
Strategy	Advantage	SD/100 hands	Effect of dealer push-22 rule
Monkey BS	-9.170%	          10.70	                  -6.111%
Wizard BS	-9.337%	          10.24	                  -6.090%
Bishop BS	-9.370%	          10.21	                  -6.035%
Straight H17 BS	-9.246%	          10.83             	  -6.267%
The actual strategy does make some changes for the push-22 rule but not as many as the other two strategies do. Here is it:

Code:
Blackjack Switch- LV rules- 8D
	Hard Hit/Stand- Dealer’s Card
	2	3	4	5	6	7	8	9	10	A
16	S	S	S	S	S	H	H	H	H	H
15	S	S	S	S	S	H	H	H	H	H
14	S	S	S	S	S	H	H	H	H	H
13	H	S	S	S	S	H	H	H	H	H
12	H	H	H	S	S	H	H	H	H	H
Always hit on 11 or less, always stand on 17 or more.H= Hit     S= Stand     
	Hard Double- Dealer’s Card
	2	3	4	5	6	7	8	9	10	A
11	D	D	D	D	D	D	D	D	D	H
10	D	D	D	D	D	D	D	D	H	H
9	H	D	D	D	D	H	H	H	H	H
8	H	H	H	H	H	H	H	H	H	H
Never double on 12 or more, never double on 7 or less.D= Double     H= Hit     
	Soft Double and Soft Hit/Stand- Dealer’s Card
	2	3	4	5	6	7	8	9	10	A
A9	S	S	S	S	S	S	S	S	S	S
A8	S	S	S	S	D	S	S	S	S	S
A7	S	D	D	D	D	S	S	H	H	H
A6	H	D	D	D	D	H	H	H	H	H
A5	H	H	D	D	D	H	H	H	H	H
A4	H	H	D	D	D	H	H	H	H	H
A3	H	H	H	D	D	H	H	H	H	H
A2	H	H	H	H	D	H	H	H	H	H
D= Double    H=Hit   S= Stand   
	Split- Dealer’s Card
	2	3	4	5	6	7	8	9	10	A
A,A	S	S	S	S	S	S	S	S	S	S
10,10	X	X	X	X	X	X	X	X	X	X
9,9	X	X	S	S	S	X	S	S	X	X
8,8	S	S	S	S	S	S	S	S	X	X
7,7	X	S	S	S	S	S	X	X	X	X
6,6	X	X	S	S	S	X	X	X	X	X
5,5	X	X	X	X	X	X	X	X	X	X
4,4	X	X	X	X	X	X	X	X	X	X
3,3	X	X	X	S	S	S	X	X	X	X
2,2	X	X	X	S	S	S	X	X	X	X
S= Split   X= Don’t split
 

halcyon1234

Well-Known Member
#3
Wouldn't it be easier to write a recursive algorithm for this? Loop through each possible player hand, and for each hand, test each dealer upcard, and for each dealer upcard, test each dealer downcard, and for each dealer downcard, test each possible next card (or stand or bust), and for each next card, test the next card, etc, etc.

That way you'll get an EXACT count of, for each have vs. upcard, how many wins/lose/pushes will come from it.
 
#4
halcyon1234 said:
Wouldn't it be easier to write a recursive algorithm for this? Loop through each possible player hand, and for each hand, test each dealer upcard, and for each dealer upcard, test each dealer downcard, and for each dealer downcard, test each possible next card (or stand or bust), and for each next card, test the next card, etc, etc.

That way you'll get an EXACT count of, for each have vs. upcard, how many wins/lose/pushes will come from it.
Easier, hell no! It took me just a couple of hours to do it on a sim. What you're proposing is a combinatorial analysis, accurate for sure but not easy. It took a lot of work to develop the first BS for blackjack using such methods.
 

aka23

Well-Known Member
#5
I added a blackjack switch decision calc to my website a few days ago at http://www.beatingbonuses.com/bjscalc.htm .

I noticed that the switching decisions differ in some cases from the calc on Wizard of Odds at http://wizardofodds.com/blackjackswitch . I believe the reason for this is the Wizard of Odds calc assumes an infinite deck and uses EVs before the dealer peaks for blackjack. Note that the EVs used in the Wizard of Odds calc are not the one in the table listed on the site, which assume 8 decks and are after dealer peaks for BJ.
 

Sonny

Well-Known Member
#6
phantom007 said:
I had wondered where you went after CC.com just seemed to vanish one day.
Good Cards!

ph007.
Welcome ph007! And congratulations on your POM. Now I’m looking forward to “story time” with a security guard. :laugh:

-Sonny-
 
#7
Index plays

Geoff says index plays alone would give you an edge at this game. But then he won't say what that is.

I have written him about counting tags. With the BJ paying double and the push on 22, I would think the tags would be different. Do you have any thoughts about counting BJ Switch and possible index plays?

This is one of the games at a favorite comp station.

Maverick
 

Kasi

Well-Known Member
#8
AM - Would your BS be the same for the Playtech game?

AKA23 - would u have a list of 5 or 10 plays that give different switch decisions than the Wiz website?

Maverick - Do you mean Geoff Hall?
 

Kasi

Well-Known Member
#10
Maverick said:
Thx.

In the game u play (is it in Nevada?) does the dealer check for BJ after you have made your play/switch decision allowing for you to switch to a BJ before he checks?

If not, what would u estimate to be the HA?
 

aka23

Well-Known Member
#11
Kasi said:
AKA23 - would u have a list of 5 or 10 plays that give different switch decisions than the Wiz website?
The only differences are hands that are extremely close calls. For example:

8/8 and 10/6 vs dealer 6. The calc on WOO says swap to create 18 and 14. My calc says keep them (and split 8s) to create 8, 8, and 16.

However, if you add up the EVs on the WOO BJS page, you get the numbers listed below, suggesting standing is the preferred option.
.146 - .213 = -.067 for stand
.1315 - .211 = -.0795 for switch
 
#12
Kasi said:
Thx.

In the game u play (is it in Nevada?) does the dealer check for BJ after you have made your play/switch decision allowing for you to switch to a BJ before he checks?

If not, what would u estimate to be the HA?
Yes the dealer peek rule is in effect for U.S. Casinos. From Blackjackswitch.com:

"The house edge following optimal switching and playing strategy is a very low 0.05% under Playtech rules. The house edge is 0.20% under Four Queens rules."

I think Snyder estimated .25% with U.S. rules.

Maverick
 
#13
Maverick said:
Yes the dealer peek rule is in effect for U.S. Casinos. From Blackjackswitch.com:

"The house edge following optimal switching and playing strategy is a very low 0.05% under Playtech rules. The house edge is 0.20% under Four Queens rules."

I think Snyder estimated .25% with U.S. rules.

Maverick
Oh yes, back when Playtech was dealing it that way, there were also offering 0.1% cashable comp on all action, so playing BJ Switch was actually positive EV even without a bonus. I made a ton on money on that game and I'm sure I'm not the only one. See that- they got greedy with the European-no-hole-card rule and it came back to get them because they didn't really understand what they were doing. Too bad they now deal it American style.
 

Geoff Hall

Well-Known Member
#14
Hi All,
As there seems to be some interest in this subject I'll throw my 2 cents worth in.

I used a revamped version of 'SBA' to get each 'switch' decision along with the corresponding house edge. Further analysis has been done by a University professor using numerical analysis and the results were very close to what I had.

I now have the following house edges that I believe are very close :-

Internet version (6 deck) 0.13%
Las Vegas (8 deck) 0.16%
US Version (switched Bj's =21) 0.59% (Hit soft 17)
US Version (switched Bj's = 21) 0.24% (Stand soft 17)

When I spoke with Wizard Of Odds, the closest plays were 14 vs 2 (we say 'Hit' WOO says 'Stand') , 9 vs 5 (we say 'Hit' WOO says 'Double') and 11 vs 9 (we say 'Hit' and WOO says 'Double'). I think that WOO changed his tables to show this but I'm not sure.

Obviously, as they are such close decisions (similar to 16 vs 10 & 12 vs 4 in regular Blackjack) then they would change with small +'ve and -'ve count indices. For example, I would :-

Stand on 14 vs 2 at +1 or higher
Double 9 vs 5 at +1 or higher
Double 11 vs 9 at +1 or higher

Other adjustments could be made for other fairly close plays, including some of the soft doubling.

Furthermore, some close 'switches' could be adjusted according to the count. For example, A,8 & 8,A could become a 'switch' verses a dealer 7 in high count situations. Maybe 'switches' affect by counts of -2 up to +2 could be memorized but it's asking a lot and the changes in play would be easier and more beneficial in my opinion.

I could get 'SBA' revamped again to produce tags for the plays but I haven't done so yet. If the game starts to expand across the USA then I am looking at producing a book that would contain this information.

Incidentally, I'm currently ay Lake tahoe, heading back to Las Vegas on Tuesday. 'Blackjack Switch' now has 19 tables in Nevada mixed in with casinos from Reno and Lake Tahoe. Furthermore, ther are 16 other casinos, in other states, that want the game, so I'm keeping my fingers crossed that the game will expand quite rapidly this year.

'Good luck' to everyone.

Best regards

Geoff
 

halcyon1234

Well-Known Member
#15
Automatic Monkey said:
Easier, hell no! It took me just a couple of hours to do it on a sim. What you're proposing is a combinatorial analysis, accurate for sure but not easy. It took a lot of work to develop the first BS for blackjack using such methods.
Sure-- but back then they didn't have-- y'know-- keyboards. =)
 
#16
Percent advantage/TC?

Geoff Hall said:
Internet version (6 deck) 0.13%
Las Vegas (8 deck) 0.16%
US Version (switched Bj's =21) 0.59% (Hit soft 17)
US Version (switched Bj's = 21) 0.24% (Stand soft 17)

'Good luck' to everyone.

Best regards

Geoff
Geoff, or anyone else,

Do you know how much % advantage each true count is worth using, say, hi-lo tags? Snyder's BBOBJ recommends 1-16 spread for 8D w/his Red 7, but he does not provide info on how switch count advantage w/counting compares to normal bj advantage. This is needed for bet sizing. Do you also have variance for optimal switching & BS?

Thank you.
 

Geoff Hall

Well-Known Member
#17
JNote said:
Geoff, or anyone else,

Do you know how much % advantage each true count is worth using, say, hi-lo tags? Snyder's BBOBJ recommends 1-16 spread for 8D w/his Red 7, but he does not provide info on how switch count advantage w/counting compares to normal bj advantage. This is needed for bet sizing. Do you also have variance for optimal switching & BS?

Thank you.
Variance is similar to regular Blackjack. Each true count indice is worth approx' 0.6% in the early count stages reducing down to 0.3% in extreme high counts.
 
#18
Geoff Hall said:
Variance is similar to regular Blackjack. Each true count indice is worth approx' 0.6% in the early count stages reducing down to 0.3% in extreme high counts.
Interesting. I had guessed the variance would be a little higher relative to the initial bets because of all the extra doubling and splitting you end up with. When I was playing it online it was a neat way to fulfill wagering requirements quickly.

When you say true count, do you mean with the High-Low system tags? I've been attacking the game with Zen, because the derated ace should properly reflect the decreased value of the ace due to the 1:1 payoff on naturals and H17 rule. But on the other hand, the increased frequency of hard doubles will give the ace some of it's value back, yes? Has anyone worked out the proper EOR's of the cards yet?
 

Geoff Hall

Well-Known Member
#19
Effect Of Removal

Automatic Monkey said:
Interesting. I had guessed the variance would be a little higher relative to the initial bets because of all the extra doubling and splitting you end up with. When I was playing it online it was a neat way to fulfill wagering requirements quickly.

When you say true count, do you mean with the High-Low system tags? I've been attacking the game with Zen, because the derated ace should properly reflect the decreased value of the ace due to the 1:1 payoff on naturals and H17 rule. But on the other hand, the increased frequency of hard doubles will give the ace some of it's value back, yes? Has anyone worked out the proper EOR's of the cards yet?
I tried various standard count systems and found that they all came out with similar results. I think that the balanced 'Zen' was where I got the edges from.

I don't know anyone who has done EOR's for the game although this would definitely be a step in the right direction to devise an appropriate count system.
 
#20
Automatic Monkey said:
I've been attacking the game with Zen, because the derated ace should properly reflect the decreased value of the ace due to the 1:1 payoff on naturals and H17 rule. But on the other hand, the increased frequency of hard doubles will give the ace some of it's value back, yes? Has anyone worked out the proper EOR's of the cards yet?
How do you feel about the two? I thought it might be more significant because of the push 22 rule.

Maverick
 
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