I'm trying to analyse some hands and I realise that I don't really have a clear set of heuristics for making calls on the flop and turn.

I understand that using the alpha value (total pot/amount to call) is only really relevant for calls where no further play will occur (i.e. river or all-in shoves). So what's the maths/strategy behind making calls on flop or turn?

At the moment I'm just using ranges and pot odds

Depending on the positions, the betsize, and the possibility of future action, I can play weak hands a few different ways. Notice that the opponents turn and river tendencies have a dramatic effect on future actions; turn and river checks are where weak hands earn ev. The more the opponent checks future streets, the more you can call the earlier streets with marginal hands. The more the opponent bets the later streets, the more we must fold the early streets. This effect and subsequent adjustments may go all the way back to preflop; I defend wider preflop vs players that check more often postflop. I fold more marginal hands preflop vs players that bet more often postflop; assuming that the starting ranges are the same.

This is a typical ev breakdown for a bluffcatcher on the turn, of which the sum of all parts is the total fraction of the pot that a bluffcatcher might win in the long run:

(River check frequency * river win frequency * pot)

(River call profit is assumed zero with unimproved bluffcatcher)

When you’re facing a turn bet, these are your ev sources. Notice that opponent mistakes can increase the sum of these profits, but never decrease the sum of these profits without changing the turn betting range.

Also notice that if we add draw potential to the ev sources, it gets much more complicated quickly. Depending on the strength of the draw and the unimproved showdown value of your hand, your ev from (River call) might increase to a positive value as might (River bet when checked to ev) and (River raise ev).

That said, unless you’re facing a large bet on the turn, I wouldn’t suggest folding the typical (pair + flushdraw) or (pair + straight draw) hands. (Pair + gutshot) is more sensitive to smaller bets and is sometimes a fold vs a typical turn bet(particularly vs tight turn bettors. Of course the strength of the draw matters (hence the term idiot end straight draws) but this is already long winded.

Good luck.

The things I look at somewhat in the order of importance. Mostly think about them all simultaneously though:

1. Betsize relative to the potsize

2. How much money is behind.

3. Rough estimation of our equity

4. Rough estimation of our playability
a. Whose range is currently favored by the board?
b. Whose ranges are favored on various runouts?
c. How likely am i to see more betting
d. What type and quality of blockers do I have?
e. What runnouts am I going to showdown?
f. Are there runouts where I can win without showdown?
g. Am I going to get paid if my hand improves?

5. Where am I at in my range?

6. What do I do with other parts of my range here?

Is it possible to hold a hand facing a bet on the flop or turn, which beats a portion of the opponents value range, yet that hand should fold?

Yes. But villain's range would have to be so value heavy as to not give you the equity required for your call.

That can happen either if villain doesn't have enough worse value hands, enough bluffs, or both.

Right. What about in a gto setting?

It might be possible just by chance improving a villain's range so much on the next card but I doubt it's possible as then I would assume the opponent starts picking bluff hands with major blocking effects to bluff appropriately.

Cool. So we can eliminate many hands that are not marginal calls from the discussion.

So the question for marginal calls is:

Can I beat my opponents draw range?

Can I get free showdown often?

Will saturating my range with near 0ev turn calls create too much river liabilities?

Let's pretend our opponent bets the river(creates 0ev call situation for lots of turn bluffcatchers unimproved on the river). He bets 50% of the time 1/2 pot and 10% of the time he bets pot. If he checks, you win 50% of the time. This is your ev after calling a bet on the turn with a hand that will be an 0ev bluffcatcher on every river:

assume pot = 1

(pot * .4 * .5) = .2 pot.

This means that if you invested more than 20% of the pot on the turn, it was an unprofitable call

or: same betting frequency, but now you win 75% of the time vs a check(this player likes to value bet thin):

(pot * .4 * .75) = .3 pots

again if you invested more than 30% of the pot on the turn, it was an unprofitable call. hint: calling 1/2 pot bet on turn is 25% investment. calling pot on turn is 33% investment.

How does draw value change this?

https://forumserver.twoplustwo.com/1...17/?highlight=

thread got sidetracked explaining why the marginal call/fold decisions are not sensitive to earning ev on future streets from a source other than (win checkdown).

I suppose the difference can be considered to be the draws. Other than that, in GTO, one plays one street at a time.

One looks the case; what his range figures to be and if he gives situation and size tells.

GTO calling on the flop (or turn) means one folds often on the turn (or river) and one plays differently only when exploiting.

I mention this because sometimes this complements our range well(like on A22 2 huhu, check back flop, bb bets turn; here no draws can call the turn usually without external factors such as strong pair power vs loose aggressive opponent, or big implied odds on hitting a straight, which just doesn't seem realistic), but sometimes having too many 0ev river calls in range is unnecessary because our busted middle pair + flushdraw or straight draw type turn calls already make up a large part of our river 0ev range; thus pure bluffcatchers don't need to be included in turn call range(such as huhu with 22 on 874r check back flop T turn big blind bets; no need to call here even if you think its 0ev.