Dear all, Recently, some young people and I started a project that may be called "Piecewise-linear ball complexes: calculations with GAP". As to me, my direct aim is to make calculations in some TQFT's (topological quantum field theories) naturally defined on PL ball complexes of any dimensions. I think, however, that calculations with PL ball complexes may be of broader interest.
So, I invite interested mathematicians to work together. As far as I know, great mathematicians of the past liked calculations, and did not limit themselves to scratching something on themselves and waiting for a flash of genius. Some first programs/functions are already written. I will give a more detailed account of this if needed. Right now let me just explain how we represent a PL ball complex. First, we assume that all vertices in the complex are numbered (from 1 to their total number N_0). Hence, in this sense, the 0-skeleton of the complex is described. Next, assuming that the k-skeleton is already given, which implies (in particular) the numeration of all k-cells, we describe the (k+1)-skeleton as the list of all (k+1)-cells, each of which, in its turn, is the set of numbers of k-cells in its boundary. Then we compose the list of length n, where n - is the dimension of the complex, whose elements are lists of 1-, ..., n-cells. Thus, a three-dimensional ball B^3 can be represented by the following PL ball complex with two vertices 1 and 2: [ [ [1,2], [1,2] ], # two one-dimensional simplexes, each with # ends 1 and 2, of which the first is referred to # in the next line as 1, the second - as 2; [ [1,2], [1,2] ], # two digons (=bigons) bounded each by # one-dimensional simplexes 1 and 2; [ [1,2] ] # the three-ball bounded by digons 1 and 2 ] With the best New Year wishes, Igor Korepanov _______________________________________________ Forum mailing list Forum@mail.gap-system.org http://mail.gap-system.org/mailman/listinfo/forum
