The signature of the pure identity theory is empty, with no functions, constants, or relations.Pure identity theory has no (non-logical) axioms. It is decidable.One of the few interesting properties t ...
For every natural mathematical structure there is a signature σ listing the constants, functions, and relations of the theory together with their valences, so that the object is naturally a σ-struct ...
In mathematical logic, a first-order theory is given by a set of axioms in some language. This entry lists some of the more common examples used in model theory and some of their properties.
