# The free-theorems-counterexamples package

This program is to verify (or to put into question) strictness conditions on free theorems that arise if a polymorphic lambda calculus is enriched by general recursion. Given a type the program either returns an instance of the corresponding unrestricted free theorem that does not hold and thereby verifies the need of the additional restrictions or it returns without finding such an instantiation and thereby suggests (but not proves) that the strictness conditions are superfluous. The underlying algorithm is described in "Automatically Generating Counterexamples to Naive Free Theorems" (FLOPS'10) by Daniel Seidel and Janis Voigtländer. A webinterface for the program is also available at http://www-ps.iai.uni-bonn.de/cgi-bin/exfind.cgi.

Related to this package you may be interested in the online free theorem generator at http://www-ps.iai.uni-bonn.de/ft that is also available offline via http://hackage.haskell.org/cgi-bin/hackage-scripts/package/free-theorems-webui. Also interesting may be the tool polyseq that generates "optimal" free theorems in a polymorphic lambda calculus with selective strictness. Polyseq can be downloaded at http://hackage.haskell.org/cgi-bin/hackage-scripts/package/polyseq but the functionality is as well provided via a webinterface at http://www-ps.iai.uni-bonn.de/cgi-bin/polyseq.cgi.

## Properties

Versions | 0.3, 0.3.0.1, 0.3.0.2, 0.3.1.0 |
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Change log | None available |

Dependencies | base (>=1), cgi, containers (>=0.1.0.1), free-theorems (>=0.3.1), haskell-src (>=1.0), haskell-src-exts (>=0.3.9), HUnit (>=1.2), mtl (>=1.0), pretty (>=1.0.0.0), syb (>=0.1.0.0), utf8-string, xhtml |

License | PublicDomain |

Author | Daniel Seidel, Joachim Breitner |

Maintainer | ds@iai.uni-bonn.de |

Category | Language |

Executables | counterexamples.cgi |

Uploaded | Wed Jul 7 09:13:07 UTC 2010 by DanielSeidel |

Distributions | NixOS:0.3.1.0 |

Downloads | 534 total (17 in last 30 days) |

Status | Docs not available [build log] Successful builds reported [all 1 reports] |

## Modules

*Language**Haskell**FreeTheorems**Variations**CounterExamples**Common*- Language.Haskell.FreeTheorems.Variations.CounterExamples.Common.AlgCommon

- Language.Haskell.FreeTheorems.Variations.CounterExamples.ExFind
*Internal*- Language.Haskell.FreeTheorems.Variations.CounterExamples.Internal.ExFindExtended

*Parser*- Language.Haskell.FreeTheorems.Variations.CounterExamples.Parser.ParseType

## Downloads

- free-theorems-counterexamples-0.3.tar.gz [browse] (Cabal source package)
- Package description (included in the package)

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