judge is a modular implementation of a decision procedure for classical and
justification logics, through a tableau-based theorem prover. It is based on
my Master's thesis, which is freely available at the Utrecht University
Repository.
judge can be installed through
Cabal:
cabal sandbox init
cabal install judge
A recommended alternative is to use Stack, for which you will need to clone the repository and do:
stack install
judge expects a logical system to be defined in the YAML
or JSON format. This file will specify the type of proof
system and the logical family (although at the moment, only the respective
values tableau and justification are recognised). It also provides the
rules of inference. See the logic directory for example
specifications.
If no target formula(s) are provided via -g, formulas are read off the
standard input. If no output file is provided via -o, the result is written
to the standard output. By default, the format is plain text; add -f LaTeX
to obtain LaTeX code instead.
For example, the following will construct proofs for theorems
of the logic LP (with c:(A→B→A) ∊ CS), and produces a PDF
file to visualise them:
judge LP \
-a "c:(A->B->A)" \
-f LaTeX \
< formulas.txt \
| pdflatex
Notable missing features are detailed on the issue tracker.
Contributions that extend judge to different logical families (modal, first
order...) or proof systems (sequent, natural deduction...) are welcomed.