The following definition are also equivalent.
- all elements of A that also belong to B
- all elements of B that also belong to A
A derived operator using minus (-) where the minus expression <math>( R1 - R2 )</math> returns anything that is only in R1
<MATH>\Large R1 \cap R2 = R1 - ( R1 - R2 ) </MATH>
- Derived using join
<MATH> \Large R1 \cap R2 = R1 \times R2 </MATH>