Randdag

C library for the counting and uniform generation of various models of DAGs (Directed Acylic Graphs).

Building

The libraries

Running make produces 2 static libraries in the build/ folder, one for each DAG model:

• libdoag.a: Directed Ordered Acyclic Graphs;
• libldag.a: Labelled Directed Acyclic Graphs.

Each library exposes a function for counting the number of graphs of given number of sources, edges an vertices and as well as two random sampling functions:

• one for the uniform random sampling of graphs with a given number of edges (xxx_unif_m);
• one for the uniform random sampling of graphs with a given number of edges and vertices.

See the header files in includes/ for more detail on the usage of each function. The counting and random sampling algorithms implemented here, as well as the different DAG models, are described in this pre-print.

Note that randdag depends on the GMP library. In order to use one of the libraries, you have to include the appropriate header file in your C code and link against the library you wish to use and GMP, e.g. -ldoag -lgmp.

The executables

Running make also produces 2 executables build/doag/doag, and build/ldag/ldag. They provide a command line interface to the counting an sampling functions. The executables should be self-documenting, try the --help flag:

usage: build/doag/doag [-h] [-c <M>] [-s <file>] [-d <file>] [-l <file>]
  -h, --help           display this help and exit
  -c, --count=<M>      count DAGs with up to M edges, defaults to 30
  -s, --sample=<file>  write a uniform DAG with M edges to <file>
  -d, --dump=<file>    dump counting info to <file>
  -l, --load=<file>    load counting info from <file>

Examples

Well-documented examples of use of the randdag libraries can be found in the examples folder. Take a look at the code and run make from this folder for building the examples.

Documentation

A succint API documentation can be generated using doxygen. To do so, run make doc and open a browser at build/doc/html/index.html.

Dependencies and Compliance

Randdag depends on the GMP library for big integer computations.

Libraries

The code for the 3 libraries should be compliant with the ANSI C standard, this means that you should expect it to compile and run on any system where you manage to compile GMP.

The makefiles however require a POSIX-compliant environment to be used. Windows users will have to build randdag by hand, sorry…

Executables

The executables have a few more compatibility requirements:

• In addition to GMP, the executables require the getopt library to be available on your system. This is the case on GNU Linux for instance.

• At the moment, we use the getrandom Linux-specific function to seed the pseudo-random number generator. This might change in the future.

• The executables are C99-compliant.

License

This work is distributed under the GPL license version 3 (see the LICENSE file).