Additive Principle

Overview

The additive principle states that two finite and disjoint sets $A$ and $B$ satisfy $|A\cup B|=|A|+|B|$

This can be generalized to any number of finite and disjoint sets in the obvious way.

Bibliography

• Oscar Levin, Discrete Mathematics: An Open Introduction, 3rd ed., n.d., https://discrete.openmathbooks.org/pdfs/dmoi3-tablet.pdf.