@INCOLLECTION{Hanus92TILP,
author = "Hanus, M.",
title = "Logic Programming with Type Specifications",
year = "1992",
chapter = "3",
pages = "91-140",
editor = "Pfenning, F.",
publisher = "MIT Press",
booktitle = "Types in Logic Programming",
abstract = {
In this chapter, we propose a framework for logic programming with
different type systems. In this framework a typed logic program
consists of a type specification and a Horn clause program
which is well-typed with respect to the type specification.
The type specification defines all types which can be used
in the logic program. Relations between types are expressed
by equations on the level of types. This permits the specification
of many-sorted, order-sorted, polymorphic and
polymorphically order-sorted type systems.

We present the declarative semantics of our framework
and two proof procedures (deduction and resolution)
for typed logic programs. An interesting application
is a type system that combines parametric polymorphism
with order-sorted typing and permits higher-order logic programming.
Moreover, our framework sheds some
new light on the r\^{o}le of types in logic programming.
},
}