Logical Connections of Statements at the Ontological Level

Introduction

In the first-order logic, there are three logical connectives , and negation where can only be applied on formulas to form new formulas, and for any formula and any model is true in if and only if is not true in

In natural languages, the connectives and negations have many forms. For example, the exclusive disjunction (exclusive or) and inclusive disjunction (inclusive or). For the negation, the forms are varying. The negation can be applied to a statement (He is not happy), a concept (not a happy man), an individual (Not he is happy) and a value of an attribute (unhappy).

To formalize the different forms of the negation in natural languages, we consider the negation at the ontological level, where the levels are a classification of the various primitives used by knowledge representation systems, firstly defined by Brachman (1979), based on which Guarino (1994) added the ontological level to the levels:

• The logical level;

• The epistemological level;

• The ontological level;

• The conceptual level, and

• The linguistic level.

We believe that every level has its own negation.

The negation at the logical level is the logical negation on formulas. In the first order logic, the negation is applied only to formulas, i.e., if is a formula then so is ; and is false if and only if is true. Hence, and are contradictory.