On expansions of o-minimal structures
Abstract
An o-minimal structure is any relational structure in any relational type in the first order predicate calculus with equality, where one symbol is reserved to be a dense linear ordering without endpoints, satisfying the following condition: that every first order definable subset of the domain is a finite union of intervals whose endpoints are in the domain or are ±•. First order definability always allows any parameters, unless explicitly indicated otherwise.