Chadwick Gambit: Software Tools for Game Theory

Command-line tools#

Gambit provides command-line interfaces for each method for computing Nash equilibria. These are suitable for scripting or calling from other programs. This chapter describes the use of these programs. For a general overview of methods for computing equilibria, see the survey of [McKMcL96].

The graphical interface also provides a frontend for calling these programs and evaluating their output. Direct use of the command-line programs is intended for advanced users and applications.

These programs take an extensive or strategic game file, which can be specified on the command line or piped via standard input, and output a list of equilibria computed. The default output format is to present equilibria computed as a list of comma-separated probabilities, preceded by the tag NE. For mixed strategy profiles, the probabilities are sorted lexicographically by player, then by strategy. For behavior strategy profiles, the probabilities are sorted by player, then information set, then action number, where the information sets for a player are sorted by the order in which they are encountered in a depth-first traversal of the game tree. Many programs take an option -D, which, if specified, instead prints a more verbose, human-friendly description of each strategy profile computed.

Many of the programs optionally output additional information about the operation of the algorithm. These outputs have other, program-specific tags, described in the individual program documentation.