Yeah, ignore what I said in the thread because I misunderstood the premise. I’d have to think about the meta game more but I’d lean towards B.
I’d also go with Player B winning this.
Simply put: Player B knows how likely he is to win at the end. Player A only knows how likely he is to win at the start.
It would be a fascinating game to play though.
I am glad there appears to be no consensus on the outcome. My Girlfriend posed the query to me and I couldn’t get my hands around who had the advantage.
I was afraid when I posted the hypothetical, everyone would post “NFM, you are a dumbass, its obvious…Player " " would win everytime.” Thank you for not saying that. 
And, FTR, I think Player B has the advantage.
Then neither player can bet big. If B bets big before the flop, A will just fold, and if A bets big, B will just fold. The players will discover this in the first five minutes. They’ll just trade the big blind back and forth for a while.
No, not at all. Heads-up play is very different than any other kind of poker. If neither player knows what the other holds, it’s much more about playing the player than playing the cards. Knowing that premium hands do not come along that often, it becomes a game of knowing when to be aggressive and when to back off. Most of the time, both players will have sub-standard hands, and most of the time the flop will miss both players in the sense of giving them a traditional starting hand like a big pair or a four flush or better.
I have a friend who is an excellent heads-up player. Maybe one of the best in the world. I made the mistake of playing against him one night, and he took $1000 off me before I knew what had happened. Since then, I’ve watched him do it to countless other players. He’s just a master at knowing when a player is getting frustrated, knowing the odds of what the player has and having an instinctual sense of when to press and when to back off. His own cards are almost irrelevant. It’s fascinating to watch, and it taught me that skill in a ring game or a tournament is nothing like the skill it takes to play heads-up for cash.
Getting back to this scenario, the player who knows the flop and turn is in a natural position to trap. And, he actually does have knowledge of the other player’s cards - the knowledge that the other player will often have very little. And if he’s really smart, he knows that the other player knows that he knows what’s coming, so the other player can’t even assume that he can push around a crap hand like 27o. There’s a huge informational asymmetry here.
The more I think about it, the more I think that the guy who knows the flop and turn has a huge advantage. He doesn’t just know four out of five cards - he knows six out of seven. He can see his likely made hand before he even has to make a bet. I don’t think it’s even a contest.
And even if he knows that he misses the flop and turn, he’s suddenly put the other player in kind of the same position he’s in - Player A knowing Player B’s hole cards becomes almost irrelevant. So he knows the guy has 36o, and he makes a big bet. The other guy raises. What now? The other guy knows that player A knows he’s got 36o, yet he raised. Is that a bluff, or is the flop coming up 458 or 33x? Suddenly Player A has no information, and can’t read the hand.
If it gets to the flop, it gets more interesting, because now player A knows exactly what player B has, while Player B knows nothing about player A. But player B still knows what the turn will be, which will allow him to play his flop hand much smarter.
If it goes to the turn, all the advantage shifts to A, as both players know what player B has, but player B doesn’t know what player A has. So it’s player B’s job to never let it get that far.
And therein lies the key. Player A has the advantage after the turn, or maybe after the flop, while Player B has the advantage pre flop. But every hand is played pre flop, while only some make it past the flop. Player B always has an opportunity to press his advantage, but Player A doesn’t always get that chance. Moreover, B has it within his power to deny A his advantage, simply by folding.
Yes, but A knows this, and the hypothetical proposes the game is being played by “two highly skilled poker players.” A can frustrate B’s advantage by folding, too. I suppose B could just bet every hand and gradually bleed A out of the Blinds. Anyway, it would be relatively easy to actually play this game, if one has a third person as dealer and something akin to a Scrabble rack. Deal B’s cards face-up, and place the flop and turn cards in the rack positioned where B can see them. If the game is playable at all, this can be discovered within a few hands.
I think it would be mildly more interesting to consider that both players are cheating (A can read B’s cards because they are marked, while B is in cahoots with the dealer who is signalling him in advance about the flop and turn) and neither knows the other one is.
Why would you need a third person as dealer? I played this last night with my little brother (who is emphatically NOT an expert). Being Player B certainly seemed easier, but I wasn’t playing against someone who knew what he was doing, so it wasn’t a meaningful test.
I think you would need a third person dealer if you did it online.
Well, someone to handle the cards, put the flop and turn where B could see them… I suppose B could be the permanent dealer, if he could be trusted. Making A the dealer at any time runs the risk of him catching a glimpse of the flop/turn cards when he makes them visible to B.
In any case, I figure within a few minutes, one of the players (A, probably) will realize his disadvantage is too great and he’ll walk away. Or if he can’t without conceding some major prize, he’ll deliberately slow-play or engage in similar methods to make the process more stressful and less calculated for B.
Consider this: Player B has a winning hand 50% of the time. That’s the law. That’s a fact.
Have you guys ever sat at a table with a rookie and he keeps going “Aw man, I folded 3-6! I would have had two-pair!”? Of course that’s annoying because, as they say, the winner is usually in the muck. The only reason we try to start with high cards- the ONLY reason- is because it’s too expensive to play every hand. So you only want to play those high percentage hands, right?
Well B’s advantage is that he pretty much knows when he’s got the 50% hand and when he doesn’t. He doesn’t have to muck his 3-6 when he knows it will hit. He doesn’t have to pay for his AK when he knows it will miss. Those are no-brainer considerations in a typical game before you even consider what the other guy has.
Even if B selects a poor hand like KK against AA (whoops!), what’s the best advantage A can hope for? 70%-30%? B is still a winner 30% of the time just by chance. With his magic power, he knows almost completely when it’s going to be one of those 30% and when it’s going to be the 70%.
Being able to start strong out of the gate trumps A’s ability to catch up two rounds later.
FTR, I’ve always advocated B’s power over A’s in an I’m-the-only-special-one-at-the-casino scenario. Think of all the money you could save on tossing or playing those 2-2s or even K-Ks when an Ace hits!
Well, ~49%, same as A. The rest of the time, it’s a push.
Nah, it’s easy. Even if you don’t want Player A *directly *propping up the community cards in a manner whereby only B can see them (which is awkward but not necessarily risky), what he would do is, after dealing out the hole cards (B’s face up), he then deals out the community cards face down, to B, at which point B can prop them up himself. I just used two paperpack books lying flat, pressed together, with the cards slipped in between them, standing up.
ETA: This method really helps to underscore B’s advantage. The community cards feel very much like (and in some important respects are) a part of B’s hand. He is privy to 5 undisclosed cards, A is privy to 2.
hey mensa you are a dumbass. it’s obvious that player B has the advantage. 
probably makes you want to reconsider your conclusion, huh. 
let the record show that mensa routinely kicks my ass on thursday nights.