On Graph-Theoretical Invariants of Combinatorial Manifolds

  • Alberto Cavicchioli
  • Fulvia Spaggiari


The goal of this paper is to give some theorems which relate to the problem of classifying combinatorial (resp. smooth)  closed manifolds up to piecewise-linear (PL) homeomorphism. For this, we use the combinatorial approach to the topology of PL manifolds by means of a special kind of edge-colored graphs, called crystallizations. Within this representation theory, Bracho and Montejano introduced in 1987 a nonnegative numerical invariant, called the reduced complexity, for any closed $n$-dimensional PL manifold.  Here we consider this invariant, and extend in this context the concept of average order first introduced by Luo and Stong in 1993, and successively investigated by Tamura in 1996 and 1998. Then  we obtain some  classification  results for  closed connected smooth low-dimensional manifolds according to  reduced complexity and average order. Finally, we answer to a question posed by Trout in 2013.

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