Logical NOR - Wikipedia, the free encyclopedia
"The NOR operation is a logical operation on two logical values, typically the values of two propositions, that produces a value of true if and only if both operands are false. In other words, it produces a value of false if and only if at least one operand is true."
When is the right side true? When both p NOR p and q NOR q are false; that is, when both p and q are true.
For a visual explanation, see the Venn diagrams on the Wikipedia page above.
Edit- Using sets:
The intersection of p and q can be expressed as the complement of the union of the complement of p and the complement of q.