double down strength of A2 and A4 vs 5

[psyduck]

For a 6-deck game and using HiLo, A2 is a weaker double down hand (TC >= 0) vs 5 than A4 (TC >= -4). I am having a hard time explaining it.

For A2, five cards 4, 5, 6, 7, and 8 can make it to 17 - 21, respectively.
For A4, five cards 2, 3, 4, 5, and 6 can make it to 17 - 21, respectively.

Where is the strength of A4 over A2?

 

[apex]

I would guess your EV is similar when doubling with both hands, but hitting A2 would be stronger since there is more room to take a small/medium card and be able to take a safe 3rd hit toward a higher total.

 

[NightStalker]

correct

I would guess your EV is similar when doubling with both hands, but hitting A2 would be stronger since there is more room to take a small/medium card and be able to take a safe 3rd hit toward a higher total.

true

 

[Canceler]

I’m going to guess that the difference in the index numbers is that for A4 all of the “good” cards are counted in HiLo, while for A2, two of them (7 & 8) are not.

But that’s where I run into the wall. I can’t give a nice explanation of just how this works. Maybe someone smarter than me can finish this off for us!

 

[Renzey]

For a 6-deck game and using HiLo, A2 is a weaker double down hand (TC >= 0) vs 5 than A4 (TC >= -4). I am having a hard time explaining it.

For A2, five cards 4, 5, 6, 7, and 8 can make it to 17 - 21, respectively.
For A4, five cards 2, 3, 4, 5, and 6 can make it to 17 - 21, respectively.

Where is the strength of A4 over A2?

I believe Apex was right. Put another way, you lose more playing efficiency by limiting yourself to only one hit with the A/2, since more hit cards (the Ace, 2, 3 and 4) will leave you wanting to hit again. With the A/4, only an Ace or deuce will do that.

 

[psyduck]

Thanks fellows. Some interesting thoughts for me to think about.

 

[Automatic Monkey]

Thanks fellows. Some interesting thoughts for me to think about.

Something else to think about- the soft doubles of A5 or less are very high variance plays, so high that if your spread is high enough, they might not be worth it. Depending on your counting system, one or two of them are even retrograde- the value goes down as the count goes up. The reason is that at high counts the chance of the dealer busting goes up, but so do the chances of you being stuck with a stiff. If you are counting aces, an ace still leaves you with a stiff, while it leaves the dealer with a nice soft hand he will get 2 chances to make.

 

[jack.jackson]

Something else to think about- the soft doubles of A5 or less are very high variance plays, so high that if your spread is high enough, they might not be worth it. Depending on your counting system, one or two of them are even retrograde- the value goes down as the count goes up. The reason is that at high counts the chance of the dealer busting goes up, but so do the chances of you being stuck with a stiff. If you are counting aces, an ace still leaves you with a stiff, while it leaves the dealer with a nice soft hand he will get 2 chances to make.

True! But remember if theres no aces left, theres no chance for either of those two things to happen, so when couning aces these hands become a nice little bonus. The less aces left in the deck, the more profitable these hands bcome.

 

[NightStalker]

I don't think so...

Depending on your counting system, one or two of them are even retrograde- the value goes down as the count goes up. The reason is that at high counts the chance of the dealer busting goes up, but so do the chances of you being stuck with a stiff.

Is this your guess or have you simulated?

 

[Automatic Monkey]

Is this your guess or have you simulated?

Both. The value of a hard double goes up rapidly as the count of high cards increases, and not so for soft doubles, and in some cases the advantage of the initial bet is going up faster than the advantage of doubling compared to hitting. It's not that big a deal, but something to consider if you are using really big bets. An ace sequencer or holecarder who sometimes is betting a large percentage of his bankroll on a single hand probably should adjust his playing strategy with this in mind.

 

[zengrifter]

In the 70s when Lawrence Revere was still teaching he recommended against doubling A2-
A5 because they did not look "normal" and the leak by not doing so was "insubstantial". zg

 

[Southpaw]

In the 70s when Lawrence Revere was still teaching he recommended against doubling A2-
A5 because they did not look "normal" and the leak by not doing so was "insubstantial". zg

My RA index for A,2 v. 5 for the ZEN count is +1, so doubling here is not something that should be in basic strategy, from a risk vs. return perspective.

SP

 

[zengrifter]

My RA index for A,2 v. 5 for the ZEN count is +1, so doubling here is not something that should be in basic strategy, from a risk vs. return perspective.

Revere meant for counting - don't double A2-5 - I always did... but I don't bother with indices for A2-5. zg

 

[psyduck]

Something else to think about- the soft doubles of A5 or less are very high variance plays, so high that if your spread is high enough, they might not be worth it. Depending on your counting system, one or two of them are even retrograde- the value goes down as the count goes up. The reason is that at high counts the chance of the dealer busting goes up, but so do the chances of you being stuck with a stiff. If you are counting aces, an ace still leaves you with a stiff, while it leaves the dealer with a nice soft hand he will get 2 chances to make.

I am not sure about the exact high counts you mentioned. For the 6deck shoe game I play, the advantage of A5 vs 4 is as follows (hilo):

TC            double              no double
-3            0.0246              0.0260
-2            0.0377              0.0307
-1            0.0503              0.0354

You can see double down at TC >= -2 offers more advantage over no double down.