Does every 3CNF propositional formula has an equivalent 2CNF propositional formula?
Definitions:
3CNF propositional formula is conjunctive normal form propositional formula, which is just conjunction $\land$ of clauses, where each clause is disjunction $\lor$ of at most 3 literals, where each literal is just boolean variable either with or without not $\lnot$ operator/connective.
2CNF propositional formula is conjunctive normal form propositional formula, which is just conjunction $\land$ of clauses, where each clause is disjunction $\lor$ of at most 2 literals, where each literal is just boolean variable either with or without not $\lnot$ operator/connective.