Models and Logical Consequence
Definition (Model)
Definition (Logical consequence)
Example
Doubt
This example shows that it may be rather difficult to prove that a formula is a logical consequence of a set of formulas. The reason is that one has to use the semantics of the language of formulas and to deal with all models of the formulas.
Proposition (Unsatisfiability)
Example
Definition (Logical equivalence)
A number of well-known facts concerning equivalence of formulas
- If there are no free occurrences of X in F then:
Logical Inference
Definition (Soundness and completness)
Substitutions
Proposition (Properties of substitutions)
Vocabulary
