# tableaux: An interactive theorem prover based on semantic tableaux

[ bsd3, program, theorem-provers ] [ Propose Tags ]

This is a simple web-based interactive theorem prover using semantic tableaux for propositional and first-order logic (cf. First-Order Logic, Raymond Smullyan, Dover). It allows step-by-step construction of proofs and runs on any web server supporting the CGI interface.

Versions [faq] 0.1, 0.2 base (==4.*), cgi (>=3001.1), containers, html (>=1.0), mtl (>=1.1), parsec (>=2.1), QuickCheck (>=2.1) [details] BSD-3-Clause Pedro Vasconcelos Pedro Vasconcelos Theorem Provers by PedroVasconcelos at 2013-04-05T16:05:04Z NixOS:0.2 tableaux.cgi 1526 total (39 in the last 30 days) (no votes yet) [estimated by Bayesian average] λ λ λ Docs not available Last success reported on 2016-12-21

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Tableaux theorem prover for first order logic
---------------------------------------------

This is a simple interactive theorem prover for first order logic
using the tableaux method. The "tableau" is a tree depicting a proof
where each node is a sentence; linear branches represent conjunctions
while forks represent disjunctions. At each step one introduces
new nodes by "breaking down" a formula into its logical
consequences. To prove a formula F it is sufficient to show that
~F is unsatisfiable, i.e. that all branches of the tableau lead

The prover is implemented in Haskell as a CGI that shows the
current proof tree and highlights one focus node
(initially the whole formula). The interface is consists of:
* navigate the proof tree (point and click)
* expand the current node
* apply resolution to the branch with the current node

Closed branches end in a "false" sentence, i.e. have been shown to
be inconsistent/unsatisfiable. To prove the original theorem one must close
all branches.

Pedro Vasconcelos <pbv@dcc.fc.up.pt>, 2009.
Tree "zipper" implementation by Krasimir Angelov & Iavor S. Diatchki, 2008.

References: First Order Logic, R. Smullyan, Dover.
On the web: http://en.wikipedia.org/wiki/Method_of_analytic_tableaux