Chapter 13: QL with Identity

In QL we can express universal and existential quantification, but we do not yet have the expressive power to formulate sentences about specific quantities. We also cannot express superlatives, such as "John is the tallest man in London." In this chapter we remedy this, and in the process we also can express a variety of properties possessed by relations. To do this, we add an additional bit of vocabulary to QL, namely identity.