re: Poker & Fold Equity Formula - Needs Explaining
The most common definition of fold equity is the direct value of getting a fold. That is, the likelihood of a fold times the size of the pot. It's not a great definition because it misses a lot of finer points, but it can be expanded:
Fold equity is the "value" of getting a fold, and then we're ignoring all the hands that are drawing dead versus us (obviously common on the river), and instead look at the average equity of the hands that fold and how often they fold. So if he folds 50% of the time with an average equity of 30%, then our fold equity is 0.5*0.3*pot size.
Slight derail: I've been toying in the past with the idea of what's essentially the bastard child of reverse implied odds
and fold equity. Two examples to show what I mean:
If a turn bet will make people fold a gutshot draw, our fold equity would be something like 10% of the pot size (his chance of hitting) for that range. Except that's not a good estimate for his equity when we have a strong hand. His EV is in fact better than that since HIS implied odds are better than just the money in the pot on the turn; we will likely pay a big price on the river when he gets there. This, I argue, should be included in estimating the value of getting a fold. It's not just the equity we fold out of the current pot, but the money we save by not paying him off on the river.
Or perhaps even more clearly: Flopping bottom set. Folding out a higher pocket pair is worth quite a bit more than just his two outs times the pot size, because if he spikes on the turn, we're often going to lose our stack.