[naphand]

Flush draws are drawing at 1.9:1 with 2 cards to come, OESD 2.2:1. By the Turn this is 4.1:1 and 4.8:1 respectively.

Of course they will make some other hands too (like runner trips or 2-pair etc.), but equally the board may go 4-suited or pair and they still lose to a better suit or FH.

The odds you need to consider then are approx. 2:1 on the flop and 4:1 and 5:1 on the Turn.

One thing to consider is that when they call the flop bet, they are drawing for 2 cards at these odds, but in reality they are likely to have to pay again on the Turn. I think HFAP or TOP deals with this in some detail, but I cannot remember it off-hand.

Betting the pot on the flop, means the caller is getting odds of 2:1, he has to call your pot-sized bet, but has that plus the pot, so 2X his bet to call. Is betting the pot enough? From this calculation any flush still has enough odds to draw even HU. If any other player is likely to call then they easily have the odds to call.

My personal feeling is you need to over-bet the pot against a draw HU. A pot bet is nice and easy, what with the "bet the pot" button, but is it enough?

If you think someone else is likely to call, then it is unlikely you can force the flush draw to draw incorrectly. You cannot let him draw free though, so a bet must be made. If the Turn is friendly to you, then a pot-sized bet is certainly correct and makes it impossible for him to draw correctly, he must fold.

However, if you consider each street as a single-card draw, (ie. you definitely bet the Turn as well) then the draws are only 4:1 and 5:1 respectively, and a pot sized bet is correct in both cases.

Can anyone explain the mathematical concept behind this? It seems to me that the odds to draw to a flush (at 2:1 with 2 cards to come) is much more relevant to limit poker, where your opponent never faces more than a few BB to draw. Can we ever consider a flush as drawing to TWO cards? where another bet is cewrtain on the Turn? Or is it more correct to only consider each as single card draws?