Terminology in Boolean implementation “The Boolean sum of four product terms is called a sum-of-products (SOP) expression.” Evaluate the correctness of this definition in digital logic design.

Introduction / Context:
Sum-of-products (SOP) and product-of-sums (POS) are foundational canonical forms in Boolean algebra, widely used in minimization and hardware realization (e.g., PAL/CPLD macrocells). This item checks fundamental terminology.

Given Data / Assumptions:

• We have several product terms (ANDed literals) combined by OR operations.
• Example mentions four product terms, but the count is not critical to the definition.
• We assess whether such an OR of product terms is an SOP.

Concept / Approach:
An SOP expression is defined as the Boolean OR (sum) of one or more Boolean product terms. A product term is an AND of literals (variables or their complements). Whether the products are minterms (all variables present) or implicants (subset of variables) does not change the “SOP” classification. Therefore, the “sum of four product terms” is indeed an SOP expression.

Step-by-Step Solution:
Identify structure: term1 + term2 + term3 + term4, where each term is an AND of literals.Match to definition: sum (OR) of products (ANDs) ⇒ SOP.Conclude the statement is correct.

Verification / Alternative check:
Textbook minimization via Karnaugh maps or Quine–McCluskey ultimately produces SOP or POS; both accept arbitrary numbers of terms.

Why Other Options Are Wrong:
“Incorrect” contradicts definitions. “Only for Karnaugh maps” is untrue; SOP is a Boolean form independent of method. Requiring minterms is unnecessary; any product terms qualify.

Common Pitfalls:
Confusing minterms with general products; believing SOP implies a unique minimal form—it does not; minimization reduces but does not redefine the SOP structure.

Final Answer:
Correct