Currently the descriptions of the problems can be downloaded in TeX Device Independent (.dvi) and Adobe PostScript (.ps) formats. The number of formats may increase.

To help the reader find their way among the hopefully increasing amount of problems, we cathegorize the problems according to some aspects. As the number of problems grows, we may introduce further cathegories and perhaps a possibility to search among the problems.
We ask contributors to place their problem in the cathegories it belongs to, or, if it doesn't fit at all, then write their suggestions about the new cathegories to introduce. Please try to briefly show the difficulty that keeps the problem open. The current aspects of sorting, and the cathegories are:

1. Type of system
• finite
• convex (dispersing, semi-dispersing)
• polygonal/polyhedral
• concave (focusing)
• mixed
• infinite
• non-interacting particles
• interacting particles
• Thermodynamic limit
2. Dimension of space
• 2D (also) open
• 3 or more ('high dimensions' or HD)
• not important
3. Investigated property
• geometry
• invariant measure
• hyperbolicity
• ergodicity
• mixing, correlation decay, limit theorems
• phase flow
• thermal equlibrium
• diffusion, heat conduction
• hydrodynamics