Sum of products (SOP)
Beginner
Writing a logic rule as a list of “this AND that” cases joined by OR.
Novice
Writing a logic rule as several AND terms joined by OR, such as (a AND b) OR (NOT a AND c). Minimizing it means using as few and as short terms as possible.
Expert
The two-level form targeted by Quine–McCluskey and Espresso. It maps directly onto programmable logic arrays but blows up for functions like parity, which is why standard-cell synthesis works on multi-level networks and uses SOP minimization only locally.
Explained in Logic synthesis (Design Flow).