"I don't think outside the box; I think of what I can do with the box." - Henri Matisse
Upon double checking, it would appear that what I wrote above is wrong. Although there are more cards that can help your double than not (i.e., you would win your double more than you'd lose it), the benefit from being able to hit more than once outweighs the value of the double. Sorry about that!
Don
Yes, I was also wondering why you should double in this situation and had in mind that the optimal play for 10 and 11 versus 17-20 is to hit. As a general rule, these optimal hole card strategy tables (e.g. from WizardOfOdds) say that doubling is never favorable against a dealer pat hand. The only situation which might be different is when the dealer has soft 17 and the H17 rule applies. I have not seen any HC strategy table addressing the S17 versus H17 issue, so I am not sure if there are any differences. Also, the surrender rule is often not addressed but I read that surrendering stiff hands versus 10,11 and 19,20 is favorable.
Oops, I accidentally deleted my last post on my smartphone. This was not the first time this happens to me. Obviously on my smartphone browser, editing a post and deletig a post is displayed on the same page and not clearly distinguished, so it easily can happen that I want to edit but it is deleted instead.
I think correct hole card strategy is:
Double hard 10-11 vs. soft 17 if dealer hits soft 17
Hit hard 10-11 vs. soft 17 if dealer stands on soft 17
Surrender hard 15-18 vs. dealer 19
Surrender hard 12-19 vs. dealer 20
Surrender anything except player BJ vs. dealer BJ
k_c
For single deck if dealer up card is ten and nothing else is known, player's EV = ~-17.15% if no surrender allowed.
If it is known that one of dealer's initial 2 cards is ten and the other is also known player's EV = ~-.08% for single deck if that is the extent of what is known.
So it seems there is value of knowing one of dealer's 2 cards is a ten and also the 2nd card, but this alone cannot result in +EV, if no surrender.
If surrender is allowed maybe +EV may be possible:
Player's EV for single deck, up card of ten, LS, nothing else known = ~-17.10%
Player's EV if 2nd card also known, LS = ~+3.04%
Player's EV for single deck, up card of ten, ES, nothing else known = ~-16.55%
Player's EV if 2nd card also known, ES = ~+6.68%
For these values to apply the up card must be ten so that wouldn't help you because you still don't know the hole card. However, if you knew the hole card was ten and also the up card you probably could gain enough to attain +EV for single deck if you are allowed to surrender.
k_c
Last edited by k_c; 12-08-2022 at 04:53 PM.
Due to my simulations done with CVData, your suggestions regarding Double/Hit hard 10-11 vs. soft 17 seem correct,
but the difference in EV is very tiny (just about 0.02 percent, for both S17 and H17 cases). I have not taken a look
at the variance but would suggest that hitting is better due to lower variance, even in the H17 case.
Furthermore, the sim runs indicate that versus dealer 19, not only 15 and above should be surrendered,
but also 13 and 14 at least. Even for 12 the difference is again so small that I would do it, because surrender lowers variance.
On the other hand, I assume that surrendering 17 and above, whilst mathematically advantageous, would look quite suspicious.
These are values I get dealt for 14 vs. 19 from top of full single deck:
These are values I get dealt for 15 vs. 19 from top of full single deck:Code:T-4 vs. T-9 hit: -44.78%, surrender: -50.00% 9-5 vs. T-9 hit: -45.73%, surrender: -50.00% 8-6 vs. T-9 hit: -47.44%, surrender: -50.00% 7-7 vs. T-9 hit: -51.25%, surrender: -50.00% T-4 vs. 8-A hit: -46.19%, surrender: -50.00% 9-5 vs. 8-A hit: -47.16%, surrender: -50.00% 8-6 vs. 8-A hit: -48.88%, surrender: -50.00% 7-7 vs. 8-A hit: -52.78%, surrender: -50.00%
Code:T-5 vs. T-9 hit: -51.98%, surrender: -50.00% 9-6 vs. T-9 hit: -51.63%, surrender: -50.00% 8-7 vs. T-9 hit: -47.46%, surrender: -50.00% T-5 vs. 8-A hit: -53.24%, surrender: -50.00% 9-6 vs. 8-A hit: -52.97%, surrender: -50.00% 8-7 vs. 8-A hit: -48.80%, surrender: -50.00%I'm sick of losing to your pat hands?On the other hand, I assume that surrendering 17 and above, whilst mathematically advantageous, would look quite suspicious.
k_c
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