CREx2 Downloads

The complete algorithm CREx2 including CREx, CREx2-ILP, and CREx2-APP can be downloaded here.

1. Obtain a Free Academic Gurobi License (
2. Download and install Gurobi Optimizer (e.g.,
3. Download CREx2
4. Extract crex2.tar.gz (tar -zxvf crex2.tar.gz)
5. If no Linux distribution is used, compile the CREx2 source code using the given Makefile. Otherwise, no further installation is needed.

A version of CREX2 without any dependency on the Gurobi Optimizer (thus only the approximation algorithms CREx and CREx2-APP are contained) can be downloaded here. For the installation of this algorithm only steps 3-5 are required.

CREx2 is executed from the command line using:
./crex2 -f <input file> [options]
use -h for more information.

For testing whether or not CREx2 is installed correctly enter:
i) ./crex2 -f example.fas or
ii) ./crex2 -f example.fas -d.

The first command produces two scenarios of rearrangements that transform the given gene orders gene_order_1 and gene_order_2 (see example.fas) into each other. Thereby, equally weighted rearrangements are used. The second command produces a table that gives only the lengths of these scenarios.

Feel free to send bug reports or any other kind of impressions or suggestions on CREx2 to