Definition:Uncertainty/Also defined as

Uncertainty: Also defined as
In their definition of uncertainty, some sources do not specify the condition that the summation is over those $k$ where $p_k > 0$, but instead define $0 \lg 0 = 0$.

This is justified as:
 * $\ds \lim_{x \mathop \to 0^+} x \lg x = 0$

from Limit to Zero from Above of x by Logarithm of x.