inclusion–exclusion principle
where |X| denotes the cardinality of the set X. This may be written
where α1 = |A| + |B| + |C|, α2 = |A ∩ B| + |A ∩ C| + |B ∩ C| and α3 = |A ∩ B ∩ C|. Now suppose that there are n sets instead of 3. Then the following, known as the inclusion–exclusion principle, holds:
where αi is the sum of the cardinalities of the intersections of the sets taken i at a time.
- Im
- IMA
- image
- imaginary axis
- imaginary number
- imaginary part
- implication
- implicit
- implicit differentiation
- implicit function theorem
- imply
- improper fraction
- improper integrals
- impulse
- incentre
- incidence
- incircle
- inclination
- inclined plane
- include
- inclusion
- inclusion–exclusion principle
- inclusive disjunction
- incommensurable
- incompatible