Idempotent Property

An operation $\star$ is idempotent if applying it to the same operand returns the operand itself: $a\star a=a$

• Example (Union): $A\cup A=A$
• Example (Intersection): $A\cap A=A$
• Example (Boolean AND): $p\wedge p=p$

Not all operations are idempotent (e.g. addition: $2+2\ne 2$).