In the present paper we find a bijection between the set of small covers over an n–cube and the set of acyclic digraphs with n labeled nodes. Using this, we give formulas of the number of small covers over an n–cube (generally, a product of simplices) up to Davis–Januszkiewicz equivalence classes and ℤ2n–equivariant homeomorphism classes. Moreover we prove that the number of acyclic digraphs with n unlabeled nodes is an upper bound of the number of small covers over an n–cube up to homeomorphism.
Choi, Suyoung  1
@article{10_2140_agt_2008_8_2391,
author = {Choi, Suyoung},
title = {The number of small covers over cubes},
journal = {Algebraic and Geometric Topology},
pages = {2391--2399},
year = {2008},
volume = {8},
number = {4},
doi = {10.2140/agt.2008.8.2391},
url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2008.8.2391/}
}
Choi, Suyoung. The number of small covers over cubes. Algebraic and Geometric Topology, Tome 8 (2008) no. 4, pp. 2391-2399. doi: 10.2140/agt.2008.8.2391
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