Incorrect or ambiguous sentence in Ch. 1

[cmencar]

The sentence

An individual who assigns a belief of 0 to an event has no confidence that the event will occur;

in Ch1_Introduction_PyMC2.ipynb does not seem to be correct or it is ambiguous. When belief is interpreted as probability, then an individual who assigns a belief of 0 to an event has full confidence that the event will not occur. If an individual assigns a belief of 0 to an event when (s)he has no confidence that the event will occur (that is, the individual is completely uncertain whether the event will occur or not) then, belief is interpreted as "necessity", not as probability. See also https://en.wikipedia.org/wiki/Possibility_theory#Necessity