# Knowledge Interchange Format (KIF)

*Knowledge Interchange Format* (KIF) is a computer-oriented
language for the interchange of knowledge among disparate
programs. It has declarative semantics (i.e. the meaning of
expressions in the representation can be understood without
appeal to an interpreter for manipulating those expressions); it
is logically comprehensive (i.e. it provides for the expression
of arbitrary sentences in the first-order predicate calculus); it
provides for the representation of knowledge about the
representation of knowledge; it provides for the representation
of nonmonotonic reasoning rules; and it provides for the
definition of objects, functions, and relations.
### Contents

Version 3.0 of the KIF manual, available in
Postscript
and TeX formats.

- Sets
- A version of von Neumann/Bernays/Godel set theory
- Sequences
- primitives for representing sequences (i.e. ordered bags or lists)
- Numbers and arithmetic
- functions and relations for basic integer and real-number arithmetic
- Relations
- functions and relations, value and handling undefined functions, variable arity, relationship to sets
- "KIF Meta"
- for representing metalinguistic knowledge about expressions in the KIF language,
such as quoted constraint expressions