Concept - Probability Basics

Definition (s.5): $P(A)$ = probability that $A$ happens; $P(A|B)$ = probability that $A$ happens given that $B$ happens (Concept - Conditional Probability).

Rules (s.5)

Rule	Formula
Complement	$P(A^C)=1-P(A)$
Disjunction	$P(A\cup B)=P(A)+P(B)-P(A\cap B)$
Conjunction	$P(A\cap B)=P(A
Independence	if $A,B$ independent: $P(A\cap B)=P(A)P(B)$
Total probability	$P(B)=\sum_{i=1}^k P(A

Why it matters

The conjunction rule gives Concept - Bayes Rule; independence is the basis of Concept - Conditional Independence in Concept - Naive Bayes.

Related

Concept - Conditional Probability, Concept - Bayes Rule, Concept - Density Estimation

Source: 03 Text Classification - Chunk 01 (s.1-30)