def __mul__(self, other):
"""Lower expectation of a gamble"""
gamble = Gamble(other)
indicator = Gamble(gamble.domain())
return murasyp.mathprog.maximize(
self | DesirSet(self.pspace() | gamble.domain()
| indicator.domain())
| DesirSet([{indicator}, {-indicator}, {()}]),
gamble, (0, {indicator: 1, -indicator: -1}))
def set_lower_pr(self, data, val):
"""Set the lower probability/prevision (expectation) of an event/gamble
:arg `data`: the gamble for which a probability/prevision value is given
:type `data`: arguments accepted by the :class:`~murasyp.gambles.Gamble`
constructor
:arg `val`: the probability/prevision value
:type `val`: a representation of :class:`~numbers.Real`
The nontrivial cone corresponing to the prevision specification is
calculated and added to the set of desirable gambles.
>>> D = DesirSet()
>>> D.set_lower_pr(Gamble({'a', 'b'}) | {'a', 'b', 'c'}, .4)
>>> assert (
... D ==
... DesirSet({Cone({Ray({'a': 1, 'c': '-2/3', 'b': 1}),
... Ray({'a': 1, 'c': 1, 'b': 1})})})
... )
.. note::
The domain of the input gamble determines the conditioning event.
"""
gamble = Gamble(data)
self.add({gamble - gamble._make_rational(val), Ray(gamble.domain())})