Himmeli

A general graph constitutes a multi-dimensional object so to draw it on a flat surface involves a coarse simplification of its nature. An equivalent would be to describe a human life by just two words. Sometimes this can be quite effective, sometimes there really is no hope of a meaningful description. In any case, a drawing of an interesting network - be it accurate or not - gives a researcher a glimpse into the abstract mathematical world of complex graphs.

Himmeli is designed for the most difficult cases of weighted and densely connected graphs were no regularities can be exploited. Consequently, large graphs take a long time to process and the textbook examples of exact combinatorial constructs might not be visualized optimally. The core algorithm is a mix of simulated annealing and molecular dynamics and employs a cell grid memory structure to reduce unnecessary computing.

This work started out as a student project, but it has since taken a life of its own. "Himmeli" is a Finnish word for a decorative handicraft made of straws that are tied together to form a regular lattice. The structure is visually striking, yet very light and portable, a perfect model for a drawing software. Himmeli is an effort to make a scientist's life easier, not harder. Thus special care has been taken to reduce the number of unnecessary formatting of input files and to ensure consistent and reliable behavior. There is no graphical user interface, but an online facility is provided for those who are not familiar with the command prompt. Finally, the source code is available under the GNU license so any enthusiastic mind can create his or her own version on any platform.

Ville-Petteri Mäkinen
FinnDiane Study Group
Folkhälsan Research Center