def _manually_create_game():
"""Creates the game manually from the spiel building blocks."""
game_type = pyspiel.GameType(
"matching_pennies",
"Matching Pennies",
pyspiel.GameType.Dynamics.SIMULTANEOUS,
pyspiel.GameType.ChanceMode.DETERMINISTIC,
pyspiel.GameType.Information.ONE_SHOT,
pyspiel.GameType.Utility.ZERO_SUM,
pyspiel.GameType.RewardModel.TERMINAL,
2, # max num players
2, # min_num_players
True, # provides_information_state
True, # provides_information_state_tensor
False, # provides_observation
False, # provides_observation_tensor
dict() # parameter_specification
)
game = pyspiel.MatrixGame(
game_type,
{}, # game_parameters
["Heads", "Tails"], # row_action_names
["Heads", "Tails"], # col_action_names
[[-1, 1], [1, -1]], # row player utilities
[[1, -1], [-1, 1]] # col player utilities
)
return game
def iterated_dominance(game_or_payoffs, mode, tol=1e-7):
"""Reduces a strategy space using iterated dominance.
See: http://www.smallparty.com/yoram/classes/principles/nash.pdf
Args:
game_or_payoffs: either a pyspiel matrix- or normal-form game, or a payoff
tensor of dimension `num_players` + 1. First dimension is the player,
followed by the actions of all players, e.g. a 3x3 game (2 players) has
dimension [2,3,3].
mode: DOMINANCE_STRICT, DOMINANCE_WEAK, or DOMINANCE_VERY_WEAK
tol: tolerance
Returns:
A tuple (`reduced_game`, `live_actions`).
* if `game_or_payoffs` is an instance of `pyspiel.MatrixGame`, so is
`reduced_game`; otherwise `reduced_game` is a payoff tensor.
* `live_actions` is a tuple of length `num_players`, where
`live_actions[player]` is a boolean vector of shape `num_actions`;
`live_actions[player][action]` is `True` if `action` wasn't dominated for
`player`.
"""
payoffs = game_payoffs_array(game_or_payoffs) if isinstance(
game_or_payoffs,
pyspiel.NormalFormGame) else np.asfarray(game_or_payoffs)
live_actions = [
np.ones(num_actions, np.bool) for num_actions in payoffs.shape[1:]
]
progress = True
while progress:
progress = False
# trying faster method first
for method in ("pure", "mixed"):
if progress:
continue
for player, live in enumerate(live_actions):
if live.sum() == 1:
# one action is dominant
continue
# discarding all dominated opponent actions
payoffs_live = payoffs[player]
for opponent in range(payoffs.shape[0]):
if opponent != player:
payoffs_live = payoffs_live.compress(
live_actions[opponent], opponent)
# reshaping to (player_actions, joint_opponent_actions)
payoffs_live = np.moveaxis(payoffs_live, player, 0)
payoffs_live = payoffs_live.reshape(
(payoffs_live.shape[0], -1))
for action in range(live.size):
if not live[action]:
continue
if method == "pure":
# mark all actions that `action` dominates
advantage = payoffs_live[action] - payoffs_live
dominated = _pure_dominated_from_advantages(
advantage, mode, tol)
dominated[action] = False
dominated &= live
if dominated.any():
progress = True
live &= ~dominated
if live.sum() == 1:
break
if method == "mixed":
# test if `action` is dominated by a mixed policy
mixture = is_dominated(live[:action].sum(),
payoffs_live[live],
0,
mode,
tol,
return_mixture=True)
if mixture is None:
continue
# if it is, mark any other actions dominated by that policy
progress = True
advantage = mixture.dot(
payoffs_live[live]) - payoffs_live[live]
dominated = _pure_dominated_from_advantages(
advantage, mode, tol)
dominated[mixture > tol] = False
assert dominated[live[:action].sum()]
live.put(live.nonzero()[0], ~dominated)
if live.sum() == 1:
break
for player, live in enumerate(live_actions):
payoffs = payoffs.compress(live, player + 1)
if isinstance(game_or_payoffs, pyspiel.MatrixGame):
return pyspiel.MatrixGame(
game_or_payoffs.get_type(), game_or_payoffs.get_parameters(), [
game_or_payoffs.row_action_name(action)
for action in live_actions[0].nonzero()[0]
], [
game_or_payoffs.col_action_name(action)
for action in live_actions[1].nonzero()[0]
], *payoffs), live_actions
else:
return payoffs, live_actions
