Inclusion-Exclusion Principle
If 
, ..., 
are finite sets, then
where
is the sum of the Cardinalities of the intersections of the sets taken 
at a time.- Legendre Relation
- Legendre's Chi-Function
- Legendre's Constant
- Legendre Series
- Legendre's Factorization Method
- Legendre's Formula
- Legendre's Quadratic Reciprocity Law
- Legendre Sum
- Legendre Symbol
- Legendre Transformation
- Lehmer Method
- Lehmer Number
- Lehmer-Schur Method
- Lehmer's Constant
- Lehmer's Formula
- Lehmer's Phenomenon
- Lehmer's Problem
- Lehmer's Theorem
- Lehmus' Theorem
- Leibniz Criterion
- Leibniz Harmonic Triangle
- Leibniz Identity
- Leibniz Integral Rule
- Leibniz Series
- Lemarié's Wavelet