A good example is "full disjunctive normal form" for propositional formulae.
If the values of all variables in a propositional formula are given, it determines a unique truth value.
In general, to avoid confusion during analysis and evaluation of propositional formulas make liberal use parentheses.
An arbitrary propositional formula may have a very complicated structure.
Any propositional formula can be reduced to its conjunctive or disjunctive normal form.
Engineers, on the other hand, put them to work in the form of propositional formulas with feedback.
If is a closed propositional formula we count itself as its only substitution instance.
The propositional formulas could then be checked for unsatisfiability using a number of methods.
The two approaches to defining stable models for sets of propositional formulas are equivalent to each other.
A propositional formula having exactly these two models is the following one: