
*** excision ***

This is an example of an index pair (for a discrete dynamical system)
which does not satisfy the excision property, as explained in the paper
"Excision-preserving Cubical Approach to the Algorithmic Computation
of the Discrete Conley Index" by K. Stolot and P. Pilarczyk.

The index map in homology cannot be computed by the program "homcubes"
because of the excision problem. Therefore, one must use the program
"homcub2l" instead, which operates on two-layer cubical sets
in order to get over this problem.
