Displaying similar documents to “Introducing Regina, the 3-manifold topology software.”

Looseness and Independence Number of Triangulations on Closed Surfaces

Atsuhiro Nakamoto, Seiya Negami, Kyoji Ohba, Yusuke Suzuki (2016)

Discussiones Mathematicae Graph Theory

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The looseness of a triangulation G on a closed surface F2, denoted by ξ (G), is defined as the minimum number k such that for any surjection c : V (G) → {1, 2, . . . , k + 3}, there is a face uvw of G with c(u), c(v) and c(w) all distinct. We shall bound ξ (G) for triangulations G on closed surfaces by the independence number of G denoted by α(G). In particular, for a triangulation G on the sphere, we have [...] and this bound is sharp. For a triangulation G on a non-spherical surface...

Around real Enriques surfaces.

Alexander Degtyarev, Vlatcheslav Kharlamov (1997)

Revista Matemática de la Universidad Complutense de Madrid

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We present a brief overview of the classification of real Enriques surfaces completed recently and make an attempt to systemize the known classification results for other special types of surfaces. Emphasis is also given to the particular tools used and to the general phenomena discovered; in particular, we prove two new congruence type prohibitions on the Euler characteristic of the real part of a real algebraic surface.