Rollout

Rollout or Roll Out may refer to:

Rollout (backgammon)

A rollout is an analysis technique for backgammon positions and moves. A rollout consists of playing the same position many times (with different dice rolls) and recording the results. The balance of wins and losses is used to evaluate the equity of the position. Historically this was done by hand, but it is now undertaken primarily by computer programs.

In order to compare two or more ways to move, rollouts can be performed from the positions after each move. Better choices will yield a more favorable position, and thus will win more times (and lose more rarely) in the end.

Computer programs usually play rollouts where the number of games is a multiple of 36, and ensure that the first dice roll is uniformly distributed. That is, 1/36th of the played games will start with a roll of 1-1, another 36th will start with 1-2, and so on. This improves the accuracy of the technique.

Rollouts depend on the availability of a good evaluator. If the computer makes mistakes in particular scenarios, the rollout results may be invalid. For example, if a computer AI's backgame strategy was weak, rollouts starting in a backgame position will skew the equity against the player who chose that strategy. When comparing moves, a weak backgame AI may favor less aggressive style. It is therefore not uncommon to see slightly different outcomes from rollouts done with different programs.

Rollout (poker)

Rollout or roll 'em out is poker jargon used for a game phase in certain poker variants. It is often incorrectly called "roll your own", to which it has similarities but from which it is fundamentally different.

Poker games with a rollout phase resemble stud poker but have significantly different strategies, because players generally receive all of their cards up front (sometimes with a draw phase), and know the final value of their hand in early betting rounds. They resemble stud poker only in that cards are revealed to other players one at a time for each betting round.

There are the same three variations on the idea as with roll your own, depending on when players are allowed to choose which card to reveal. They can either be forced to arrange the order of their cards before any betting begins ("choose before"), or they can also be allowed to choose cards in later rounds based on information found in earlier rounds ("choose after"). In the latter case, the revealing can be made simultaneously or in turn.