
*** torus ***

In this example the homology module of the torus is computed.

A chain complex of the torus is stored in a file and its homology 
module is computed by the program "homchain".

The file begins with the phrase "chain complex" (or "chaincomplex"), 
then the maximal dimension of cells is indicated in the form 
"maximal dimension 2", and afterwards the boundaries of cells are defined 
for each dimension separately. The names of the cells can be any sequences 
of characters isolated by blank characters (the space, the tabulator or end 
of line), not beginning with '+', '-', ':', '*', ';' and '=', and different 
from the words "#", "0", "boundary", "image" and "dimension".
If the boundary of any cell is zero, then the formula for its boundary 
can be omitted or entered as "b cell3 = 0" or simply "b cell3". If not all 
the cells of some dimension appear in the boundaries of other cells and their 
boundaries are 0 (like isolated points, for example), the number of cells 
for this dimension must be declared in the form "dimension 0: 33".
