Propositional formula
（重定向自Propositional expression）
![Engineering symbols have varied over the years, but these are commonplace. Sometimes they appear simply as boxes with symbols in them.](/Images/godic/202502/04/Propositional_formula_connectives_11456.png")
![The engineering symbol for the NAND connective (the 'stroke') can be used to build any propositional formula. The notion that truth (1) and falsity (0) can be defined in terms of this connective is shown in the sequence of NANDs on the left, and the derivations of the four evaluations of a NAND b are shown along the bottom. The more common method is to use the definition of the NAND from the truth table.](/Images/godic/202502/04/Propositional_formula_NANDs1457.png")
![A truth table will contain 2n rows, where n is the number of variables (e.g. three variables](/Images/godic/202502/04/Propositional_formula_maps_11457.png")
![Steps in the reduction using a Karnaugh map. The final result is the OR (logical](/Images/godic/202502/04/Propositional_formula_maps_21458.png")
In propositional logic, a propositional formula is a type of syntactic formula which is well formed and has a truth value. If the values of all variables in a propositional formula are given, it determines a unique truth value. A propositional formula may also be called a propositional expression, a sentence, or a sentential formula.