4 ms·
Completeness for FOL specifically says that semantic implications (in the language of FOL) have syntactic proofs. There are many concepts that are inexpressible
by tylerhou 1y ago
Completeness for FOL specifically says that semantic implications (in the language of FOL) have syntactic proofs. There are many concepts that are inexpressible in FOL (for example, the class of all graphs which contain a cycle).