2011年2月12日 星期六

Texas Holdem strategy

Strategy

Most poker authors recommend a tight-aggressive approach to playing Texas hold 'em. This strategy involves playing relatively few hands (tight), but betting and raising often with those that one does play (aggressive). Although this strategy is often recommended, some professional players successfully employ other strategies as well.
Almost all authors agree that where a player sits in the order of play (known as position) is an important element of Texas hold 'em strategy, particularly in no-limit hold'em. Players who act later have more information than players who act earlier. As a result, players typically play fewer hands from early positions than later positions.
Because of the game's level of complexity, it has received some attention from academics. One attempt to develop a quantitative model of a Texas hold'em tournament as an isolated complex system has had some success, although the full consequences for optimal strategies remain to be explored. In addition, groups at the University of Alberta and Carnegie Mellon University are developing poker playing programs utilizing techniques in game theory and artificial intelligence.


Starting hands

A pair of aces is statistically the best hand to be dealt in Texas Hold'em Poker
Because there are only two cards dealt to each player, it is easy to characterize all of the starting hands. There are 52 × 51 ÷ 2 = 1,326 distinct possible combinations of two cards from a standard 52-card deck. Because no suit is more powerful than another, many of these can be equated for the analysis of starting-hand strategy. For example, although "J♥ J♣" and "J♦ J♠" are distinct combinations of cards, they are of equal value as starting hands.
Viewed this way there are only 169 different hole-card combinations. Thirteen of those hands would be pairs, from 2 through ace. There are 78 ways to have two cards of different rank (12 possible hands containing an ace, 11 possible hands containing a king and no ace, 10 possible hands containing a queen and no ace or king, etc.). Hole cards can both be used in a flush if they are suited, but pairs are never suited, so there would be 13 possible pairs, 78 possible suited non-pairs, and 78 possible unsuited non-pairs, for a total of 169 possible hands.Suited starting cards are stronger than unsuited hands, although the magnitude of this strength in different games is debated.
Because of this limited number of starting hands, most strategy guides involve a detailed discussion of each of these 169 starting hands. This separates hold 'em from other poker games where the number of starting card combinations forces strategy guides to group hands into broad categories. Another result of this small number is the proliferation of colloquial names for individual hands.

Strategic differences in betting structures

Texas Hold'em is commonly played both as a "cash" or "ring" game and as a tournament game. Strategy for these different forms can vary.

Cash games

Prior to the invention of poker tournaments, all poker games were played with real money where players bet actual currency (or chips which represented currency). Games which feature wagering actual money on individual hands are still very common and are referred to as "cash games" or "ring games".
The no-limit and fixed-limit cash game versions of hold 'em are strategically very different. Doyle Brunson claims that "the games are so different that there are not many players who rank with the best in both types of hold 'em. Many no-limit players have difficulty gearing down for limit, while limit players often lack the courage and 'feel' necessary to excel at no-limit."]Because the size of bets is restricted in limit games, the ability to bluff is somewhat curtailed. Since one is not (usually) risking all of one's chips in limit poker, players are sometimes advised to take more chances.
Lower stakes games also exhibit different properties than higher stakes games. Small stakes games often involve more players in each hand and can vary from extremely passive (little raising and betting) to extremely aggressive (many raises). The difference of small stakes games have resulted in several books dedicated to only those games.


Tournaments

Texas hold 'em is often associated with poker tournaments largely because it is played as the main event in many of the famous tournaments, including the World Series of Poker's Main Event, and is the most common tournament overall. Traditionally, a poker tournament is played with chips that represent a player's stake in the tournament. Standard play allows all entrants to "buy-in" for a fixed amount and all players begin with an equal value of chips. Play proceeds until one player has accumulated all the chips in play or a deal is made among the remaining players to "chop" the remaining prize pool. The money pool is redistributed to the players in relation to the place they finished in the tournament. Only a small percentage of the players receive any money, with the majority receiving nothing. "The percentages are not standardized, but common rules of thumb call for one table" (usually nine players) "to get paid for each 100 entrants," according to poker author Andrew N. S. Glazer, in his book, The Complete Idiot's Guide to Poker.A good rule of thumb is that close to 10% of players will be paid in a tournament. As a result the strategy in poker tournaments can be very different from a cash game.
Proper strategy in tournaments can vary widely depending on the amount of chips one has, the stage of the tournament, the amount of chips others have, and the playing styles of one's opponents. Although some authors still recommend a tight playing style, others recommend looser play (playing more hands) in tournaments than one would otherwise play in cash games. In tournaments the blinds and antes increase regularly, and can become much larger near the end of the tournament. This can force players to play hands that they would not normally play when the blinds were small, which can warrant both more loose and more aggressive play.

Evaluating your hand

One of the most important things in Texas hold'em is knowing how to evaluate your hand. The strategy of playing each hand can be very different according to the strength of your hand, for example on a strong hand a player might want to try to appear weak in order not to scare off other players with weaker hands and on a weak hand a player might try to bluff other players into folding. There are several ways to evaluate your hand strength, two of the most common are counting outs and using calculators.
  • Counting outs - the reasoning behind this method is in counting cards that are still in the deck which in combination with the cards in your hand will give you a combination with very high chances of winning.
Those cards are called "outs" and your hand strength can be measured by how many outs are still in the deck (if there are many outs then the probability to get one of them is high and therefore you have a strong hand). The following chart determines the probability of hitting outs (bettering the player's hand) based on how many cards are left in the deck and the draw type. Note that a higher number of outs directly corresponds to a high win percentage.
OutsOne Card %Two Card %One Card OddsTwo Card OddsDraw Type
12%4%4623Backdoor Straight or Flush (Requires two cards)
24%8%2212Pocket Pair to Set
37%13%147One Overcard
49%17%105Inside Straight / Two Pair to Full House
511%20%84One Pair to Two Pair or Set
613%24%6.73.2No Pair to Pair / Two Overcards
715%28%5.62.6Set to Full House or Quads
817%32%4.72.2Open Straight
919%35%4.11.9Flush
1022%38%3.61.6Inside Straight & Two Overcards
1124%42%3.21.4Open Straight & One Overcard
1226%45%2.81.2Flush & Inside Straight / Flush & One Overcard
1328%48%2.51.1
1430%51%2.30.95
1533%54%2.10.85Flush & Open Straight / Flush & Two Overcards
1634%57%1.90.75
1737%60%1.70.66

  • Two Times Rule and Four Times Rule: Multiplying the number of outs by two or four gives a reasonable approximation to the One Card % or Two Card %, respectively, in the above table.
  • Calculators: calculators are poker tools that calculate the odds of your hand (combined with the cards on the table if there are any) to win the game. Calculators provide precise odds but they can't be used in live games and mostly used on Internet poker games. 

Texas Hold'em examples


Examples 

Sample showdown

Here's a sample showdown:
Board
4 of clubsKing of spades4 of hearts8 of spades7 of spades
Bob
  Ace of clubs4 of diamonds  
Carol
  Ace of spades9 of spades  
Ted
  King of heartsKing of diamonds  
Alice
  5 of diamonds6 of diamonds  
Each player plays the best 5-card hand they can make with the seven cards available. They have
Bob4 of clubs4 of hearts4 of diamondsAce of clubsKing of spadesThree fours, with ace, king kickers
CarolAce of spadesKing of spades9 of spades8 of spades7 of spadesAce-high flush
TedKing of spadesKing of heartsKing of diamonds4 of clubs4 of heartsFull house, kings full of fours
Alice8 of spades7 of spades6 of diamonds5 of diamonds4 of hearts8-high straight
In this case, Ted's full house is the best hand, with Carol in 2nd, Alice in 3rd and Bob last.

[edit]Sample hand

The blinds for this example hand
Here is a sample game involving four players. The players' individual hands will not be revealed until the showdown, to give a better sense of what happens during play:
Compulsory bets: Alice is the dealer. Bob, to Alice's left, posts a small blind of $1, and Carol posts a big blind of $2.
Pre-flop: Alice deals two hole cards face down to each player, beginning with Bob and ending with herself. Ted must act first because he is the first player after the big blind. He cannot check, since the $2 big blind plays as a bet, so he folds. Alice calls the $2. Bob adds an additional $1 to his $1 small blind to call the $2 total. Carol's blind is "live" (see blind), so she has the option to raise here, but she checks instead, ending the first betting round. The pot now contains $6, $2 from each of three players.
Flop: Alice now burns a card and deals the flop of three face-up community cards, 9♣ K♣ 3♥. On this round, as on all subsequent rounds, the player on the dealer's left begins the betting. In this case it is Bob, who checks. Carol opens for $2, Ted has already folded and Alice raises another $2 (puts in $4, $2 to match Carol and $2 to raise), making the total bet now facing Bob $4. He calls (puts in $4, $2 to match Carol's initial bet and $2 to match Alice's raise). Carol calls as well, putting in her $2. The pot now contains $18, $6 from the last round and $12 from three players this round.
Turn: Alice now burns another card and deals the turn card face up. It is the 5♠. Bob checks, Carol checks, and Alice checks; the turn has been checked around. The pot still contains $18.
River: Alice burns another card and deals the final river card, the 9♦, making the final board 9♣ K♣ 3♥ 5♠ 9♦. Bob bets $4, Carol calls, and Alice folds (Alice's holding was A♣ 7♣; she was hoping the river card would be a club to make her hand a flush).
Showdown: Bob shows his hand of Q♠ 9♥, so the best five-card hand he can make is 9♣ 9♦ 9♥ K♣ Q♠, for three nines, with a king-queen kicker. Carol shows her cards of K♠ J♥, making her final hand K♣ K♠ 9♣ 9♦ J♥ for two pair, kings and nines, with a jack kicker. Bob wins the showdown and the $26 pot.

[edit]Kickers and ties

Because of the presence of community cards in Texas hold 'em, different players' hands can often run very close in value. As a result, it is common for kickers to be used to determine the winning hand and also for two hands (or maybe more) to tie. A kicker is a card which is part of the five-card poker hand, but is not used in determining a hand's rank. For instance, in the hand A-A-A-K-Q, the king and queen are kickers.
The following situation illustrates the importance of breaking ties with kickers and card ranks, as well as the use of the five-card rule. After the turn, the board and players' hole cards are as follows.
Board (after the turn)
8 of spadesQueen of clubs8 of hearts4 of clubs
Bob
King of heartsQueen of spades
Carol
Queen of hearts10 of diamonds
At the moment, Bob is in the lead with a hand of Q♠ Q♣ 8♠ 8♥ K♥, making two pair, queens and eights, with a king kicker. This beats Carol's hand of Q♥ Q♣ 8♠ 8♥ 10♦ by virtue of his king kicker.
Suppose the final card were the A♠, making the final board 8♠ Q♣ 8♥ 4♣ A♠. Bob and Carol still each have two pair (Queens and eights), but both of them are now entitled to play the final ace as their fifth card, making their hands both two pair, queens and eights, with an ace kicker. Bob's king no longer plays, because the ace on the board plays as the fifth card in both hands, and a hand is only composed of the best five cards. They therefore tie and split the pot. However, had the last card been Jack or lower (except a Queen or Eight which would make a full house, or a Ten which would give Carol a higher second pair), Bob's King would have stayed in game and he would have won.

(from wiki)