NTI is a free software distributed under the terms of the GNU Lesser General Public License, version 3 or any later version. It is developed and maintained by Étienne Payet.

Usage: java -jar nti.jar <file> [action] [options]

NTI tries to prove (non)termination of the program in the provided file.

• For logic programs, the implemented techniques are described in [Payet & Mesnard, TOPLAS'06] and [Payet, TPLP'25].
• For TRSs, the implemented technique uses the dependency pair (DP) framework: first, it decomposes the initial set of DP problems into subproblems using sound DP processors, then it tries to prove that the unsolved subproblems are infinite using the approaches of [Payet, TCS'08], [Payet, LOPSTR'18] and [Payet, JAR'24].

file has to conform to the TPDB syntax specification (see here and here). It has one of the following suffixes:

• .pl for a pure logic program
• .ari for a TRS or an SRS in the ARI format
• .xml for a TRS or an SRS in the old XML format
• .trs for a TRS in the old, human readable, format
• .srs for an SRS in the old, human readable, format

action (optional) can be:

• -h|--help: print this help
• --version: print the version of NTI
• -print: print the program in the given file
• -stat: print some statistics about the program in the given file
• -prove: run a (non)termination proof of the program in the given file (THIS IS THE DEFAULT ACTION)

options (optional) can be:

• -v: verbose mode (for printing proof details in the final output)
• -t=n: set a time bound on the nontermination proofs (n is the time bound in seconds)
• -cTI=path: set the path to cTI (for proving termination of logic programs)
  If no path to cTI is set, then only nontermination proofs are run for logic programs