About

Octant is a pre-processor that can be used to accelerate the verification of generalized reachability properties on Petri nets. It takes advantage of structural reductions and work by projecting an initial reachability property into a simpler one, that can be checked on the reduced version of the Petri net.

The tool is named after the Octant map projection proposed by Leonardo da Vinci in 1508; the first known example of a polyhedral map projection.

This project was initially developed inside TiPX, a Petri net explorer.

Installation

You can build an executable by compiling the project from its source, using the accompanying Makefile. The tool is written in OCaml and uses the Dune build system. You can also download the latest build of the tool, compiled for Linux, called octant.exe, on the “linux” branch of the repository

Running the tool

./octant.exe command1 command2 ... commandn

Octant is a CLI tool that operates over its parameters as if they were a sequence of commands for a stack-based language. Each command takes its arguments from the stack and/or from the command-line.

• p means ‘pop’ (stack argument)
• r means ‘reads a command-line argument’
• 1 means pushes one value
• * means pushes multiple values

Additionally, a global environment consists in bindings of the form

• name => formula
• name => bundle (that is: a Petri net, an initial marking, and possibly a tfg).

Environment

load : r -> 0 - (implicit) - Load the given Petri net, put it as a bundle in the environment with the name ’net’. E.g.: load “file.net”.
bind : rp -> 0 - Binds the element on the stack to the given name. E.g.: bind special-net.
set : rp -> 0 - Synonym to bind.
get : r -> 1 - (implicit) - Gets the element associated to the given identifier in the environment. Pushes it. E.g.: get special-net.

Formulas

form : r -> 1 - Parse and push the given formula(s) on the stack (as a list). The reference bundle is the last found in the environment.
load-forms : r -> 1 - Read formulas from the given file and push them on the stack (as a list). The reference bundle is the last found in the environment.
project : p -> 1 - Projects a list of formulas (popped from the stack). The reference bundle must have a tfg. Pushes the resulting list of formulas.
tproject : rp -> 1 - Projects with a time limit.

Display

quiet : -> 0 - Quiet mode (prints only necessary information, e.g. verdicts).
smt-format : -> 0 - Use smt-lib format when printing formulas.
print : p -> 0 - Pops and prints the topmost stack element.
fprint : p -> 0 - Full print: print the topmost stack element, with details.
nl : -> 0 - Prints a blank line (separator).

Others

time : -> 0 - Prints the delay since the previous time command. The first time command does not print anything.
dup : p -> 2 - Duplicate the argument on top of the stack.
pop : p -> 0 - Discards the topmost stack element.
help : -> 0 - Display this help.

References

• Amat, N, Le Botlan, D, Dal Zilio, S. Project and Conquer: Fast Quantifier Elimination for Checking Petri Nets Reachability. International Conference on Verification, Model Checking, and Abstract Interpretation (VMCAI), To appear. 2024.

Dependencies

The code repository includes OCaml libraries developed by Didier Le Botlan (outside this project) located inside folder lib/.

License

This software is distributed under the GPLv3 license.

Authors

• Nicolas Amat - LAAS/CNRS
• Didier Le Botlan - LAAS/CNRS