What is a probability function?
1. Given a discrete random variable
Given a discrete random var (See: What is a discrete random variable? ),
Each value in the range (not the domain!) has an associated probability p.
This association/relation is defined as a probability function
f(x) = p
See also:
Laws
Given a range X for a discrete random variable,
f(x) > 0 for all x ∈ X
Sum of all x is 1.