Citip

Information Theoretic Inequality Prover (C++/CLI version).

This program is derived from Xitip which is based on ITIP. Xitip was made by Rethnakaran Pulikkoonattu, Etienne Perron and Suhas Diggavi. ITIP was created by Raymond W. Yeung and Ying-On Yan.

Why another fork?

Originally, I just wanted to replace the GTK frontend by a more convenient CLI interface, because I found the GUI inconvenient. CLI based applications are better for automatization and also require fewer run-time dependencies.

Another reason was to provide a public platform for possible continued development of the application. I was at the time unable to get in contact with any of the original authors of Xitip (emails were dead), and there was (AFAIK) no public VCS.

I didn't plan to do much apart from that, but by now all the source files have been completely rewritten. The main differences to Xitip are:

• replace the GTK frontend by a simple CLI frontend
• ported to the free software GLPK library for linear programming
• extend the accepted grammar in a few places
• compilation requires a C++11 compliant compiler and recent versions of flex and bison

For a more detailed list of changes see CHANGES.rst and ultimately the commit history.

If you have any ideas and/or patches to contribute, don't be shy!, just open an issue or send me a pull-request.

Build

First, you need to obtain a version of GLPK suited for your platform. It is highly likely that you can grab GLPK from your distribution's official repositories. Otherwise, see their website for instructions.

In the best case scenario, Citip can now be built by simply running the make command. Everything put together, your build process could look as follows:

sudo apt-get install libglpk-dev
git clone https://github.com/coldfix/Citip.git
cd Citip
make

If this fails, try building with cmake as follows:

make clean
mkdir build
cd build
cmake ..
make

Please report if the compilation or flex/bison source generation fails. If the problem is only with flex/bison, I can provide generated sources.

Usage

The command line interface is pretty basic at the moment. The inequality to be proven and constraints can be passed either as command line arguments or (if no command line arguments are provided or the last one is -) via STDIN.

The first command line argument (or line from STDIN) is taken to be the inequality to be proven. All the others are constraints. Example:

$ ./Citip 'I(X;Y|Z) <= I(X;Y)'

The information expression is either:
    1. FALSE, or
    2. a non-Shannon type inequality

(exit code = 1)


$ ./Citip 'I(X;Y|Z) <= I(X;Y)' 'H(Z) = 0'

The information expression is TRUE.

(exit code = 0)


$ ./Citip 'I(X;;Y|Z) <= I(X;Y)'

ERROR: syntax error, unexpected ';', expecting NAME
in row 0 col 5:

    I(X;;Y|Z) <= I(X;Y)
        ^^

(exit code = 2)

Note that the location indicators for syntax errors are only approximate.

The program exit code can be used to determine the outcome. The meaning of exit codes is as follows:

0 - Inequality is TRUE
1 - Truth can not be decided by Citip
2 - Error

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.