Over the past year I've been doing a large number of computations with GAP and as I require much of the same data to be computed over & over again, I've been storing it. One of the items I've been storing is the StructureDescription of a large number of groups. I realize that for groups, especially p-groups, the information obtained isn't always that useful, but sometimes it is. For more complicted groups (lots of factors in the order) this seems to be very expensive to compute, and very slow (hence the reason to store it).
I've run into a problem, which may be intrinsic to the problem, may be a problem with gap, or might be a problem with our computer or operating system. Perhaps someone can tell me which. Ok, a perhaps stupid computation, but let's ignore that part: I've computed the structure descriptions of all the groups of order 256 (56092 total) except for the ones numbered 56083 through 56087. I believe all of these are of rank 7. I've now either run out of memory and had GAP quit, or I've brought the machine down 3 times when trying to compute the result for 56083 or 56087. With memory set at a max of 50G the computation runs out of memory and quits. I've tried 100G and 80G with the same result - a crash. The machine does have 128G of ram and several times that in swap space (as well as 16 CPUs). Any ideas what the problem may be? One further question and a remark: Are there any other implementations of a computation of structure description that gives more useful information that that in gap? I still believe that it makes sense to have a community accessible archive of many such "standard" computations as structure descricption, although when I raised that question at the recent computational group theory conference in Ohio, there was not a great deal of enthusiasm for the idea. With the current cheap price of storage (especially compared to that of memory and the time expended for comutation), it would seem to make sense, to me at least. Keith _______________________________________________ Forum mailing list [email protected] http://mail.gap-system.org/mailman/listinfo/forum
