def __init__(self,arity,S=None,dom=2):
""" Create a new min/max operation. """
Operation.__init__(self,arity,dom)
# Default operation
if S is None:
S = frozenset(frozenset([i]) for i in range(arity))
self.S = frozenset(MinMax.sperner(map(lambda s: frozenset(s),S)))
def __init__(self,dom,pos,vals):
Operation.__init__(self,3,dom)
self.pos = tuple(pos)
self.vals = vals
