DNF

DNF is an acronym that can refer to several concepts depending on the domain. The two most common meanings are Did Not Finish in competitive contexts and Disjunctive Normal Form in logic and computer science.

Did Not Finish (DNF) is used in racing and other timed events to indicate that a participant started but did not complete the course or competition. A result may be recorded as DNF when a competitor withdraws due to injury, fatigue, or disqualification, or when the event was halted before they could finish. DNF is typically distinguished from DNS, which stands for Did Not Start. In official results, a DNF entry shows that a competitor did not achieve a finishing time, but their attempt is acknowledged up to the point of withdrawal.

Disjunctive Normal Form (DNF) is a standard form of expressing a Boolean formula in propositional logic. A Boolean expression is in DNF if it is a disjunction (OR) of one or more conjunctions (AND) of literals, where a literal is a variable or its negation. For example, (A ∧ B) ∨ (¬C ∧ D) is in DNF. DNF is related to CNF (Conjunctive Normal Form) and can be obtained from more complex expressions via logical equivalences. Canonical DNF lists every minterm that makes the expression true, providing a unique, exhaustive representation, though it can be lengthy for large variables.

In summary, DNF commonly denotes either a non-finishing outcome in sports or a formal logical structure, with the intended meaning usually clear from context.