explain to me the mathematics of a blocking bet

[Jerrod Ankenman]

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]

As is often the case, The Mathematics of Poker explains the concept far better than I could. Blocking bets are a powerful and IMO underappreciated tactic, especially on the river.
Mook

[/ QUOTE ]

Can't find blocking bet in the index or table of context of
The Mathematics of Poker . There is a chapter on
bet sizing. Can you cite the page from MOP on blocking
bets?
Believe blocking bets was created by a pseudo math guy.

[/ QUOTE ]

We call these bets "preemptive bets" and discuss the concept in the discussion of the no-limit AKQ game, p 164-177.

Preemptive betting reduces the opponent's equity by decreasing his ability to value bet and bluff; while the play has negative ex-showdown value with a mediocre hand, this value is less negative than the value of checking and facing a mixture of value bets and bluffs.

[/ QUOTE ]

Good post. However, when villain can spot a blocking bet and will raise with both better and worse made hands + bluffs, then the blocking bet is horribly -EV against that player. Far better to check to induce a bluff against that player.

[/ QUOTE ]

This will avail him nothing if you properly mix value hands in with your mediocre hands - obviously it is easily exploitable if you preemptively bet with mediocre hands only. If the player raise-bluffs with hands worse than your mediocre hands, you gain value when you have a value hand and he has a bluff.

"the blocking bet is horribly -EV against that player..."

It's true that against your opponents' value raises and bluff-raises you lose the amount of the preemptive bet, but you lose a significant amount anyway when you check your mediocre hands, since you'll be indifferent to calling or folding, and the amount you lose by preemptive betting is smaller. In the no limit AKQ solution, IIRC, the ratio of value hands to mediocre hands is 5:2 or something. So you're making this smaller bet with a lot of value hands.

Now if you're arguing that the opponents you play against in practice play worse if you don't make preemptive bets, then fine, exploit them by not doing it. I'm just pointing out that in optimal NL strategies, preemptive betting of the type I describe is almost certainly present.