Range – Equity – Maximum, or REM, was a concept created with the first printing of Professional No-Limit Hold ‘em: Volume I. It's a terrific way to evaluate your plays in no-limit holdem and think logically about your decisions.
Playing winning poker is the process of getting information and then using it to make the most profitable play. The REM process is one of the easiest ways to execute this. The three steps in the REM process are “Range, Equity, Maximize.”
The first step in REM is defining your opponents range. There are over a thousand possible poker hands, but based on your opponents decisions throughout the hands, we can narrow this range down to something more manageable. To properly execute the Range step, there are a number of sub-steps to consider.
Know Thy Opponent – Everything about your opponent will affect whether or not certain hands are in the opponent's range. A tight player, under the gun, will not raise garbage. I've made a list of the things you can know about your opponent that will help you gain the most information: Preflop Standards, Betting Patterns or Amounts in Various Situations, Particular Actions on Specific Streets or with Specific Hand Types, Physical Tells, Betting Pace. (Read More: all of these categories are fleshed out in the book, Professional No-Limit Hold ‘em: Volume I)
Reevaluate What You Know – Every street should involve a reassessment of your opponents range based on each new action on each new street. This should also involve reassessing previously eliminated hands. Opponents are capable of and willing to mix up their play by raising hands like eight-five suited.
Things to remember: put your opponent on a range of hands. Eliminate hands you are fairly sure they don't have. Narrow their range further by observing specific things about a player, like betting patterns and timing tells. Pay attention even after you've folded. Reassess on each new action.
The second step in REM is to analyze the information that we got during the first step. This is simply calculating your equity against your opponents range. Off the table, this step can be outsourced into PokerStove, but on the table, you need a few additional skills for estimating your equity on the fly.
To estimate your equity on the fly, think about your opponents hands that you are a big favorite over and those hands you are a big underdog to. If your opponents range primarily consists of hands that you are a big underdog to, your equity is probably bad. If your opponent primarily holds hands that you are a big favorite to, your equity is probably good.
Never overlook folding equity. Sometimes, against an opponent range, using your fold equity will be the most effective way to win the pot.
Maximizing means making the best decision given your equity in the hand. Your choice of actions is always to check, fold, bet, raise, or call. Your goal is to maximize your winnings by selecting the highest EV action.
Checking – You benefit from checking behind when you have a weak hand and little folding equity, and there is a chance that you will improve to the best hand. A weak gutshot draw to the nuts is a great example of when to check behind. If you are first to act, checking to your opponent works well if your opponents are aggressive and you want them to bet.
Betting – Betting is appropriate when you want to extract profit, punish draws, or make others fold. The first question to answer is whether you want your opponents in the pot or whether you want them out of the pot. When you want them to stay in, you execute a bet that is sized to extract value. When you want them to go away, you should execute a well-sized bluff.
Folding, Calling, or Raising with Drawing Hands – With a weak draw with poor pot equity, choose between folding and calling. Call with good implied odds and fold with bad. With a strong draw and good pot equity, choose between raising and calling. Call with good implied odds, and raise with bad.