Visualising (the kernel of) free software repositories
Imagine that you want to find out which packages cannot be installed together in your latest and preferred free software distribution... how would you go about it?
One could try and install together all possible combination of packages, but a free software repository contains several tens of thousands packages, and more than one hundred thousand dependencies and conflicts, so this approach might be interesting only if you really dont know how to best use your account on a Google farm, and you don't care about wasting energy.
One could be a bit smarter, have a look at what has been done in the EDOS and Mancoosi european projects, and program a SAT solver to test these combinations of packages without actually installing them.
Or you could take a completely different approach, and come up with a revolutionary new way of looking at free software repositories.
In a few hours, I am taking a plain to Szeged, to attend the 8th ESEC/FSE conferece, where Jerôme Vouillon is going to show how to extract from free software distributions a co-installability kernel which is much more compact, can be visualised easily, and allows by simple visual inspection to answer this kind of questions in a few seconds.
To give you an example, from the main section of the Ubuntu 10.10 alpha 2 distribution, that contains 7277 packages, one can extract a very simple graph, that easily fits in an A4 page, and which shows all co-installability issues.
Looking at the graph, it is easy to spot immediately a problem with the distribution: you can only install ubuntu-desktop with the pulseaudio audio library, and not with the many other options which are available (like alsa): you can check by yourslef in the picture below
If you know Jerôme, you know that there is also some fantastic piece of software around, and you will be eager to try it... don't wait any longer, you can learn more about COINST by just clicking here.
And by the way, Jerôme's COINST tool got the Distinguished Artifact Award, which will presented at the conference.
It happens that the award is sponsored by Microsoft Research, which posted a nice announcement about it, and we can be happy to see Microsoft Research recognising the importance of the research challenges emerging from Free Software.