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location: dlvex


The DLV-EX project has migrated to DLV-Complex. DLV-Complex is a very powerful ASP system, which, besides external predicates, explicitly supports (recursive) functions, sets, and lists, along with libraries for their manipulations.

If you want, you can still download the last versions of DLV-EX binaries available and some libraries, in the download section, but please note that the DLV-EX project is no longer maintained, thus no new releases/updates are scheduled in the future. For new releases, other important events and full documentation regarding DLV-COMPLEX please refer to the DLV-Complex page.

DLV-EX: The Project

DLV-EX is an Answer Set Programming System extending DLV by External Predicates, which features a framework aimed at enabling ASP to deal with external sources of computation. This feature is realized by the introduction of “parametric” external predicates, whose extension is not specified by means of a logic program but implicitly computed through external code. It is explicitly addressed the issue of invention of new information coming from external predicates, in form of new, and possibly infinite, constant symbols.

DLV-EX is based on the DLV system.

If you designed a nice external predicate, tell us.

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The Team


Francesco Calimeri, Giovambattista Ianni, Susanna Cozza

Former team members

Adriana Pietramala (student), Maria Carmela Santoro (student)

Prompters and helpers

Simona Perri, Wolfgang Faber, Gerald Pfeifer, Nicola Leone

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Some ready-made (compiled) dynamic libraries can be downloaded here. They have to be considered as "betas", since they are currently developed and tested. Feedbacks are useful and welcome, so please download them freely. For further information on how to exploit libraries have a look at the documentation. Please note that updates will be available later on, so come back to this page.


DEBT - We have developed an integrated command-line environment aimed at helping in testing external built-ins predicates. This may be very useful for users who define their own built-ins. DEBT can be downloaded here, and it is gathered with its related documentation.

Latest Version

This is an OLD version of the system, which is no longer maintained.

Please have a look at the notes below. You may also want to have a look at some benchmarks.

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Related Works

It is worth noting that our work shares many aspects with the work carried out by Thomas Eiter, Giovambattista Ianni, Roman Schindlauer, and Hans Tompits. They introduce HEX programs, which are nonmonotonic logic programs admitting higher-order atoms as well as external atoms, and extend the answer-set semantics accordingly. A web page with a prototype and some references is available here.

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Release a full version for Windows. Bugfixes. This is supposed to be the last release. The project is moving to DLV-Complex.

Bugfixes and speedups. Support for VI-restricted programs implemented.

"Beta" version, much improved. Carries many bugfixes and improvements.

First stable version, even if still a "beta".

First working version, experimental.

...did not carry a real version identification.

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Selected Publications

[1] F. Calimeri, S. Cozza, G. Ianni, "External Sources of Knowledge and Value Invention in Logic Programming", Annals of Mathematics and Artificial Intelligence, 2007, to appear. PDF

[2] F. Calimeri, S. Cozza, G. Ianni, "Decidable fragments of Logic Programming with Value Invention", Proceedings of the 10th European Conference on Logics in Artificial Intelligence (JELIA'06) in Logics in Artificial Intelligence, Lecture Notes in Computer Science (LNCS), v. 4160, pp. 95-110, September 2006, Liverpool, UK, Springer Verlag, GmbH Tiergartenstrasse 17, 69121, Heidelberg Germany, ISBN 3-540-39625-X. PDF

[3] F. Calimeri, G. Ianni, "External sources of computation for Answer Set Solvers", Proceedings of the 8th International Conference on Logic Programming and Nonmonotonic Reasoning (LPNMR'05), Diamante, Italy, 5-8 September 2005, Springer Verlag. PDF

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