"On the second to last betting round, Alice's hand is certainly behind and she faces a $1 call to win a $10 pot against a single opponent. There are four cards remaining in the deck that make her hand a certain winner. Her odds of drawing to one of those cards is 10.5:1 (8.7 percent). Since the pot lays 10:1, Alice will lose money by calling if there is no future betting. Since Alice expects to always make an additional $1 when she makes her draw, and always fold when she misses her draw (lose no additional bets), her implied pot odds
are 11:1 ($10 plus the additional $1 bet, to her $1 call). This call now has a positive expectation." - wikipedia
and similar for reverse. what changes if i want to calculate from the flop?