Bluff (poker)

# Bluff (poker)

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Encyclopedia
In the card game of poker
Poker
Poker is a family of card games that share betting rules and usually hand rankings. Poker games differ in how the cards are dealt, how hands may be formed, whether the high or low hand wins the pot in a showdown , limits on bet sizes, and how many rounds of betting are allowed.In most modern poker...

, a bluff is a bet or raise made with a hand which is not thought to be the best hand. To bluff is to make such a bet. The objective of a bluff is to induce a fold by at least one opponent who holds a better hand. The size and frequency of a bluff determines its profitability to the bluffer. By extension, the term is often used outside the context of poker to describe the act of making threats one cannot execute.

## Pure bluff

A pure bluff, or stone-cold bluff, is a bet or raise with an inferior hand that has little or no chance of improving. A player making a pure bluff believes he can win the pot only if all opponents fold. The pot odds
Pot odds
In poker, pot odds are the ratio of the current size of the pot to the cost of a contemplated call. Pot odds are often compared to the probability of winning a hand with a future card in order to estimate the call's expected value....

for a bluff are the ratio of the size of the bluff to the pot. A pure bluff has a positive expectation
Expected value
In probability theory, the expected value of a random variable is the weighted average of all possible values that this random variable can take on...

(will be profitable in the long run) when the probability of being called by an opponent is lower than the pot odds for the bluff.

For example, suppose that after all the cards are out, a player holding a busted drawing
Draw (poker)
A poker player is drawing if they have a hand that is incomplete and needs further cards to become valuable. The hand itself is called a draw or drawing hand. For example, in seven-card stud, if four of a player's first five cards are all spades, but the hand is otherwise weak, they are drawing to...

hand decides that the only way to win the pot is to make a pure bluff. If the player bets the size of the pot on a pure bluff, the bluff will have a positive expectation if the probability of being called is less than 50%. Note, however, that the opponent may also consider the pot odds when deciding whether to call. In this example, the opponent will be facing 2-to-1 pot odds for the call. The opponent will have a positive expectation for calling the bluff if the opponent believes the probability the player is bluffing is at least 33%.

## Semi-bluff

In games with multiple betting rounds, to bluff on one round with an inferior or drawing hand that might improve in a later round is called a semi-bluff. A player making a semi-bluff can win the pot two different ways: by all opponents folding immediately or by catching a card to improve the player's hand. In some cases a player may be on a draw but with odds strong enough that he is favored to win the hand. In this case his bet is not classified as a semi-bluff even though his bet may force opponents to fold hands with better current strength.

For example, a player in a stud poker
Stud poker
Stud poker is any of a number of poker variants in which each player receives a mix of face-down and face-up cards dealt in multiple betting rounds. Stud games are also typically non-positional games, meaning that the player who bets first on each round may change from round to round...

game with four spade-suited cards showing (but none among their downcards) on the penultimate round might raise, hoping that his opponents believe he already has a flush. If his bluff fails and he is called, he still might be dealt a spade on the final card and win the showdown
Showdown (poker)
In poker, the showdown is a situation when, if more than one player remains after the last betting round, remaining players expose and compare their hands to determine the winner or winners....

(or he might be dealt another non-spade and try his bluff again, in which case it is a pure bluff on the final round rather than a semi-bluff).

## Bluffing circumstances

Bluffing may be more effective in some circumstances than others. Bluffs have a higher expectation when the probability of being called decreases. Several game circumstances may decrease the probability of being called (and increase the profitability of the bluff):
• Fewer opponents who must fold to the bluff.
• The bluff provides less favorable pot odds to opponents for a call.
• A scare card comes that increases the number of superior hands that the player may be perceived to have.
• The player's betting pattern in the hand has been consistent with the superior hand they are representing with the bluff.
• The opponent's betting pattern suggests the opponent may have a marginal hand that is vulnerable to a greater number of potential superior hands.
• The opponent's betting pattern suggests the opponent may have a drawing
Draw (poker)
A poker player is drawing if they have a hand that is incomplete and needs further cards to become valuable. The hand itself is called a draw or drawing hand. For example, in seven-card stud, if four of a player's first five cards are all spades, but the hand is otherwise weak, they are drawing to...

hand and the bluff provides unfavorable pot odds to the opponent for chasing the draw.
• Opponents are not irrationally committed to the pot (see sunk cost fallacy).
• Opponents are sufficiently skilled and paying sufficient attention.

The opponent's current state of mind should be taken into consideration when bluffing. Under certain circumstances external pressures or events can significantly impact an opponent's decision making skills.

## Optimal bluffing frequency

If a player bluffs too infrequently, observant opponents will recognize that the player is betting for value
Value (poker)
In poker, the strength of a hand is often called its value; however, in the context of poker strategy the term is more often used to describe a betting tactic, a bet for value. This bet is intended to increase the size of the pot, by inducing opponents to call...

and will call with very strong hands or with drawing
Draw (poker)
A poker player is drawing if they have a hand that is incomplete and needs further cards to become valuable. The hand itself is called a draw or drawing hand. For example, in seven-card stud, if four of a player's first five cards are all spades, but the hand is otherwise weak, they are drawing to...

hands only when they are receiving favorable pot odds
Pot odds
In poker, pot odds are the ratio of the current size of the pot to the cost of a contemplated call. Pot odds are often compared to the probability of winning a hand with a future card in order to estimate the call's expected value....

. If a player bluffs too frequently, observant opponents snap off his bluffs by calling or re-raising. Occasional bluffing disguises not just the hands a player is bluffing with, but also his legitimate hands that opponents may think he may be bluffing with. David Sklansky
David Sklansky
-Life and career:Sklansky was born and raised in Teaneck, New Jersey, where he graduated from Teaneck High School in 1966. He attended the University of Pennsylvania, but left before graduation. He returned to Teaneck and passed multiple Society of Actuaries exams by the time he was 20, and worked...

, in his book The Theory of Poker, states "Mathematically, the optimal bluffing strategy is to bluff in such a way that the chances against your bluffing are identical to the pot odds your opponent is getting."

Optimal bluffing also requires that the bluffs must be performed in such a manner that opponents cannot tell when a player is bluffing or not. To prevent bluffs from occurring in a predictable pattern, game theory
Game theory
Game theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...

suggests the use of a randomizing agent to determine whether to bluff. For example, a player might use the colors of his hidden cards, the second hand on his watch, or some other unpredictable mechanism to determine whether to bluff.

Example (Texas Hold'em)

Again, let us return to the examples in The Theory of Poker:

when I bet my \$100, creating a \$300 pot, my opponent was getting 3-to-1 odds
from the pot. Therefore my optimum strategy was . . . [to make] the odds against
my bluffing 3-to-1.

Since the dealer will always bet with (nut hands) in this situation, he should bluff with (his) "Weakest hands/bluffing range" 1/3
of the time in order to make the odds 3-to-1 against a bluff.

Ex:
On the last betting round (river), Worm has been betting a "semi-bluff" drawing hand with: A♠ K♠ on the board:

10♠ 9♣ 2♠ 4♣
against Mike's A♣ 10♦ hand.

The river comes out:

2♣

The pot is currently 30 dollars, and Worm is contemplating a 30 dollar bluff on the river. If Worm does bluff in this situation, he is giving Mike 2-to-1 pot odds
Pot odds
In poker, pot odds are the ratio of the current size of the pot to the cost of a contemplated call. Pot odds are often compared to the probability of winning a hand with a future card in order to estimate the call's expected value....

to call with his two pair (10's and 2's).

Important: In these hypothetical circumstances, Worm will have the nuts 50% of the time, and be on a busted draw 50% of the time. Worm will bet the nuts (100%) of the time, and bet with a bluffing hand (using mixed optimal strategies
Strategy (game theory)
In game theory, a player's strategy in a game is a complete plan of action for whatever situation might arise; this fully determines the player's behaviour...

):

Where s is equal to the percentage of the pot that Worm is bluff betting with and x is equal to the percentage of busted draws Worm should be bluffing with to bluff optimally.

Pot = 30 dollars.
Bluff bet = 30 dollars.

s = 30(pot) / 30(bluff bet) = 1.

Worm should be bluffing with his busted draws:

x = Where s = 1

Assuming 4 trials, Worm has the nuts 2 times, and has a busted draw 2 times. (EV = Expected Value
Expected value
In probability theory, the expected value of a random variable is the weighted average of all possible values that this random variable can take on...

)
Worm bets with the nuts (100% of the time) Worm bets with the nuts (100% of the time) Worm bets with a busted draw (50% of the time) Worm checks with a busted draw (50% of the time)
Worm's EV = 60 dollars Worm's EV = 60 dollars Worm's EV = 30 dollars (if Mike folds) and -30 dollars (if Mike calls) Worm's EV = 0 dollars (since he will neither win the pot, nor lose 30 dollars on a bluff)
Mike's EV = -30 dollars (because he would not have won the original pot, but lost to Worm's value bet on the end) Mike's EV = -30 dollars (because he would not have won the original pot, but lost to Worm's value bet on the end) Mike's EV = 60 dollars (if he calls, he'll win the whole pot, which includes Worm's 30 dollar bluff) and 0 dollars (if Mike folds, he can't win the money in the pot) Mike's EV = 30 dollars (assuming Mike checks behind with the winning hand, he will win the 30 dollar pot)

Under the circumstances of this example: Worm will bet his nut hand 2 times, for every one time he bluffs against Mike's hand (assuming Mike's hand would lose to the nuts and beat a bluff). This means that (if he called all three bets) Mike would win 1 time, and lose two times, and would break even against 2-to-1 pot odds. This also means that Worm's odds against bluffing is also 2-to-1 (since he will value bet twice, and bluff once).

Say in this example, Worm decides to use the second hand of his watch to determine when to bluff (50% of the time). If the second hand of the watch is between 1 and 30 seconds, Worm will check his hand down (not bluff). If the second hand of the watch is between 31 and 60 seconds, Worm will bluff his hand. Worm looks down at his watch, and the second hand is at 45 seconds, so Worm decides to bluff. Mike folds his two pair saying, "the way you've been betting your hand, I don't think my two pair on the board will hold up against your hand." Worm takes the pot by using optimal bluffing frequencies.

Please note: This example is meant to illustrate how optimal bluffing frequencies work. Because it was an example, we assumed that Worm had the nuts 50% of the time, and a busted draw 50% of the time. In real game situations, this is not usually the case.

The purpose of optimal bluffing frequencies is to make the opponent (mathematically) indifferent
Principle of indifference
The principle of indifference is a rule for assigning epistemic probabilities.Suppose that there are n > 1 mutually exclusive and collectively exhaustive possibilities....

between calling and folding. Optimal bluffing frequencies are based upon game theory and the Nash Equilibrium
Nash equilibrium
In game theory, Nash equilibrium is a solution concept of a game involving two or more players, in which each player is assumed to know the equilibrium strategies of the other players, and no player has anything to gain by changing only his own strategy unilaterally...

, and assist the player using these strategies to become unexploitable. By bluffing in optimal frequencies, you will typically end up breaking even on your bluffs (in other words, optimal bluffing frequencies are not meant to generate positive expected value from the bluffs alone). Rather, optimal bluffing frequencies allow you to gain more value from your "value bets," because your opponent is indifferent between calling or folding when you bet (regardless to whether it's a value bet or a bluff bet).

## Bluffing in other games

Although bluffing is most often considered a poker term, similar tactics are useful in other games as well. In these situations, a player makes a play that shouldn't be profitable unless an opponent misjudges it as being made from a position capable of justifying it. Since a successful bluff requires deceiving one's opponent, it occurs only in games where the players conceal information from each other. In games like chess and backgammon where both players can see the same board, they should simply make the best legal move available. Examples include:
• Contract Bridge
Contract bridge
Contract bridge, usually known simply as bridge, is a trick-taking card game using a standard deck of 52 playing cards played by four players in two competing partnerships with partners sitting opposite each other around a small table...

: Psychic bid
Psychic bid
Psychic bid is a bid in contract bridge that grossly misstates the power and/or suit lengths of one's hand. It is used deliberately to deceive the opponents. Normally, the psychic bid is made with a weak hand, overstating its overall strength, the length and strength in a particular suit, or both...

s and falsecards are attempts to mislead the opponents about the distribution of the cards. A risk (common to all bluffing in partnership games) is that a bluff may also confuse the bluffer's partner. Psychic bids serve to make it harder for the opponents to find a good contract or to accurately place the key missing cards with a defender. Falsecarding (a tactic available in most trick taking card games) is playing a card that would naturally be played from a different hand distribution in hopes that an opponent will wrongly assume that the falsecarder made a natural play from a different hand and misplay a later trick on that assumption.
• Stratego
Stratego
Stratego is a board game featuring a 10×10 square board and two players with 40 pieces each. Pieces represent individual officers and soldiers in an army. The objective of the game is to either find and capture the opponent's Flag or to capture so many of the opponent's pieces that he/she cannot...

: Much of the strategy in Stratego revolves around identifying the ranks of the opposing pieces. Therefore depriving your opponent of this information is valuable. In particular, the "shoreline bluff" involves placing the flag in an unnecessarily vulnerable location in hopes that the opponent won't look for it there.