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Computational homotopy of finite regular CW-spaces. (English) Zbl 1311.55008
This paper describes an approach to the computational homotopy of CW-spaces. Computational advantages are obtained by considering spaces that a tessellated in the sense that the space is the union of the closure of its $$n$$-cells and all closures of the $$n$$-cell have face posets isomorphic to that of some fixed polytope. The case where this is a permutahedral one is particularly useful. The authors describe a “zig-zag” homotopy retraction approach to reducing the number of cells of low-dimensional lattice spaces. It is important that this approach is algorithmic. Applications to feature recognition in low-dimensional images is given as an illustration of the technique. The ideas have been implemented in the HAP (homological algebra package http://www.gap-system.org/Pacjkages/hap.html) for the GAP computational system. Sessions with the package are given in the paper.

##### MSC:
 55N99 Homology and cohomology theories in algebraic topology 55-04 Software, source code, etc. for problems pertaining to algebraic topology
##### Software:
CrystCat; GAP; Graphviz; HAP; happermutahedral; Kenzo; PLEX
Full Text:
##### References:
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