adds test to show function
creates is_monotone function
creates is_superadditive function
creates tests for is_superadditive and passes them
removes player_list from required attributes
sets up functions for properties of payoff_vector
change starting paragraph
creates is_nullplayer function
creates is_symmetry function
fixes error in is_nullplayer when using strings
adds lots more examples
is_nullplayer passes all tests
Changed show method to be slightly nicer on the eye. Needs to be changed in docs
Merge branch '16332' of github.com:theref/sage-game-theory into 16332
Changed show output to read payoff vector
rewrites nullplayer
Merge branch '16332' of https://github.com/theref/sage-game-theory into 16332
fixes show tests
Fixes #10 including all associated documentation
fixes is_symmetry and updates tests for payoff_vector dictionary