1.1 Basic Concepts

The two central concepts introduced in this section are what we call first-order formula and first-order model. Intuitively, we perceive of first-order formulas as descriptions of certain situations. First order models correspond to such situations.

• 1.1.1 Vocabularies

• 1.1.2 First-Order Models

• 1.1.3 An Example Model

• 1.1.4 Exact Models

• 1.1.5 First-Order Languages

• 1.1.6 Building Formulae

• 1.1.7 Subformulae, Free Variables

• 1.1.8 Free Variables versus Bound Variables

• 1.1.9 Notation