# What is a probability function?

# 1. Given a discrete random variable

Given a discrete random var (See: What is a discrete random variable?^{ᛦ} ),

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.