System Description: Twelf — A Meta-Logical Framework for Deductive Systems

  • Frank Pfenning
  • Carsten Schürmann
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 1632)


Twelf is a meta-logical framework for the specification, implementation, and meta-theory of deductive systems from the theory of programming languages and logics. It relies on the LF type theory and the judgments-as-types methodology for specification [HHP93], a constraint logic programming interpreter for implementation [Pfe91], and the meta-logic M2 for reasoning about object languages encoded in LF [SP98]. It is a significant extension and complete reimplementation of the Elf system [Pfe94].

Twelf is written in Standard ML and runs under SML of New Jersey and MLWorks on Unix and Window platforms. The current version (1.2) is distributed with a complete manual, example suites, a tutorial in the form of on-line lecture notes [Pfe], and an Emacs interface. Source and binary distributions are accessible via the Twelf home page


Logic Program Logic Programming Object Language Operational Semantic Deductive System 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. DHKP96.
    Gilles Dowek, Thérèse Hardin, Claude Kirchner, and Frank Pfenning. Unification via explicit substitutions: The case of higher-order patterns. In M. Maher, editor, Proceedings of the Joint International Conference and Symposiumon Logic Programming, pages 259–273, Bonn, Germany, September 1996. MIT Press.Google Scholar
  2. HHP93.
    Robert Harper, Furio Honsell, and Gordon Plotkin. A framework for defining logics. Journal of the Association for Computing Machinery, 40(1):143–184, January 1993.zbMATHMathSciNetGoogle Scholar
  3. Pfe.
    Frank Pfenning. Computation and Deduction. Cambridge University Press. In preparation. Draft from April 1997 available electronically.Google Scholar
  4. Pfe91.
    Frank Pfenning. Logic programming in the LF logical framework. In Gérard Huet and Gordon Plotkin, editors, Logical Frameworks, pages 149–181. Cambridge University Press, 1991.Google Scholar
  5. Pfe94.
    Frank Pfenning. Elf: A meta-language for deductive systems. In A. Bundy, editor, Proceedings of the 12th International Conference on Automated Deduction, pages 811–815, Nancy, France, June 1994. Springer-Verlag LNAI 814. System abstract.Google Scholar
  6. Pfe96.
    Frank Pfenning. The practice of logical frameworks. In Hélène Kirchner, editor, Proceedings of the Colloquium on Trees in Algebra and Programming, pages 119–134, Linköping, Sweden, April 1996. Springer-Verlag LNCS 1059. Invited talk.Google Scholar
  7. PS98.
    Frank Pfenning and Carsten Schürmann. Algorithms for equality and unification in the presence of notational definitions. In T. Altenkirch, W. Naraschewski, and B. Reus, editors, Types for Proofs and Programs. Springer-Verlag LNCS, 1998. To appear.Google Scholar
  8. RP96.
    Ekkehard Rohwedder and Frank Pfenning. Mode and termination checking for higher-order logic programs. In Hanne Riis Nielson, editor, Proceedings of the European Symposium on Programming, pages 296–310, Linköping, April 1996. Springer-Verlag LNCS 1058.Google Scholar
  9. SP98.
    Carsten Schürmann and Frank Pfenning. Automated theorem proving in a simple meta-logic for LF. In Claude Kirchner and Hélène Kirchner, editors, Proceedings of the 15th International Conference on Automated Deduction (CADE-15), pages 286–300, Lindau, Germany, July 1998. Springer-Verlag LNCS 1421.Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1999

Authors and Affiliations

  • Frank Pfenning
    • 1
  • Carsten Schürmann
    • 1
  1. 1.Department of Computer ScienceCarnegie Mellon UniversityUSA

Personalised recommendations