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#1
10-07-2007, 07:31 AM
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In a S17, H16 game
Can anyone tell me why doubling A4 and 5 are mathematically better than doubling A2 and 3?
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#3
10-07-2007, 09:44 AM
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Re: In a S17, H16 game
[ QUOTE ]
Can anyone tell me why doubling A4 and 5 are mathematically better than doubling A2 and 3? [/ QUOTE ] I'll try (though you may wish to move this to the appropriate forum for the best answer). The issue is the ability to rehit. One only doubles down here against stiffs (dealer showing three through six in a 6-deck game). With this in mind, the goal is to maximize EV. Doubling A5 against a stiff is straightforward. An A, 2, 3, 4 and 5 improve the hand (P = 5/13). The other cards have no effect (P = 8/13; a total less than 17 is the same as zero). The downside to doubling down is not getting a third card. Here, it's only an A where you'd like to get one more card (P = 1/13), and an A here isn't horrible, as you still have a chance to push against some of the range where the dealer stands (a 17, of course). Doubling A2: Improves with 4, 5, 6, 7, and 8 (still P = 5/13). Other cards equal zero (still P = 8/13). The difference is in losing the rehit. Here, you'd like to rehit if you got an A, 2, 3, or 4 (P = 4/13), and only one of these, the 4, allows a push against a dealer 17.
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#5
10-07-2007, 11:50 PM
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Re: In a S17, H16 game
[ QUOTE ]
Is this a blackjack question? There's no rhyme or reason to it. Just run the monte carlos and see which does better. [/ QUOTE ] It's blackjack, and it's a legitimate question...no Monte Carlo needed, as you'd only double down against a dealer 3 - 6. I do have a table of the EV of these decisions, but he wanted to know why, so I shared that with him.
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#6
10-08-2007, 10:19 PM
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Re: In a S17, H16 game
[ QUOTE ]
[ QUOTE ] Is this a blackjack question? There's no rhyme or reason to it. Just run the monte carlos and see which does better. [/ QUOTE ] It's blackjack, and it's a legitimate question...no Monte Carlo needed, as you'd only double down against a dealer 3 - 6. I do have a table of the EV of these decisions, but he wanted to know why, so I shared that with him. [/ QUOTE ] Edward O. Thorp solved this and other questions by monte carlo. Then he published the tables.
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#7
10-16-2007, 11:11 AM
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Re: In a S17, H16 game
[ QUOTE ]
[ QUOTE ] [ QUOTE ] Is this a blackjack question? There's no rhyme or reason to it. Just run the monte carlos and see which does better. [/ QUOTE ] It's blackjack, and it's a legitimate question...no Monte Carlo needed, as you'd only double down against a dealer 3 - 6. I do have a table of the EV of these decisions, but he wanted to know why, so I shared that with him. [/ QUOTE ] Edward O. Thorp solved this and other questions by monte carlo. Then he published the tables. [/ QUOTE ] Yes, I have the tables (Schlesinger redid them for all combinations). The OP wanted to know WHY one was better, not THAT one was better. There is rhyme or reason, so I was sharing that with him.
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#8
10-08-2007, 07:01 AM
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Re: In a S17, H16 game
[ QUOTE ]
[ QUOTE ] Can anyone tell me why doubling A4 and 5 are mathematically better than doubling A2 and 3? [/ QUOTE ] I'll try (though you may wish to move this to the appropriate forum for the best answer). The issue is the ability to rehit. One only doubles down here against stiffs (dealer showing three through six in a 6-deck game). With this in mind, the goal is to maximize EV. Doubling A5 against a stiff is straightforward. An A, 2, 3, 4 and 5 improve the hand (P = 5/13). The other cards have no effect (P = 8/13; a total less than 17 is the same as zero). The downside to doubling down is not getting a third card. Here, it's only an A where you'd like to get one more card (P = 1/13), and an A here isn't horrible, as you still have a chance to push against some of the range where the dealer stands (a 17, of course). Doubling A2: Improves with 4, 5, 6, 7, and 8 (still P = 5/13). Other cards equal zero (still P = 8/13). The difference is in losing the rehit. Here, you'd like to rehit if you got an A, 2, 3, or 4 (P = 4/13), and only one of these, the 4, allows a push against a dealer 17. [/ QUOTE ] Ah... I see now. Thank you.
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#9
10-16-2007, 11:11 AM
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Re: In a S17, H16 game
[ QUOTE ]
Ah... I see now. Thank you. [/ QUOTE ] No problem. Glad to help.
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