def CPSD(game):
"""
conditional strict pure-strategy dominance criterion for IEDS
The criterion is 'conditional' in that it will eliminate strategies that
are dominated given all available data in a partial game.
"""
dominated = {r:set() for r in game.roles}
for r in game.roles:
for s1, s2 in RSG.product(game.strategies[r], repeat=2):
if s1 == s2:
continue
for profile in game:
v1 = v2 = float('-inf')
try:
v1 = game.getPayoff(profile, r, s1)
except KeyError:
continue
try:
v2 = game.getPayoff(profile.remove(r,s1).add(r,s2), r, s2)
except KeyError:
break
if v1 >= v2:
break
if v1 < v2:
dominated[r].add(s1)
return game.subgame(strategies={r:set(game.strategies[r]) - dominated[r] \
for r in game.roles})
def PSD(game):
"""
confirmed strict pure-strategy dominance criterion for IEDS
This criterion differs from CPSD in that it will only declare a strategy
dominated if all profiles in which both it and the dominating strategy
appear have payoff data available.
"""
dominated = {r:set() for r in game.roles}
for r in game.roles:
for s1, s2 in RSG.product(game.strategies[r], repeat=2):
if s1 == s2:
continue
data_missing = False
for profile in game:
v1 = v2 = float('-inf')
try:
v1 = game.getPayoff(profile, r, s1)
v2 = game.getPayoff(profile.remove(r,s1).add(r,s2), r, s2)
if v1 >= v2:
break
except KeyError:
data_missing = True
break
if v1 < v2 and not data_missing:
dominated[r].add(s1)
return game.subgame(strategies={r:set(game.strategies[r]) - dominated[r] \
for r in game.roles})
