Coloured knots and permutations representing 3-manifolds.
Grasselli, Luigi (1996)
Mathematica Pannonica
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Grasselli, Luigi (1996)
Mathematica Pannonica
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Maria Rita Casali (1992)
Revista Matemática de la Universidad Complutense de Madrid
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In this work, we prove that every closed, orientable 3-manifold M which is a two-fold covering of S branched over a link, has type six.
Luigi Grasselli (1990)
Revista Matemática de la Universidad Complutense de Madrid
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We describe a combinatorial algorithm for constructing all orientable 3-manifolds with a given standard bidimensional spine by making use of the idea of bijoin (Bandieri and Gagliardi (1982), Graselli (1985)) over a suitable pseudosimplicial triangulation of the spine.
Luigi Grasselli (1987)
Disertaciones Matemáticas del Seminario de Matemáticas Fundamentales
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Tomoe Motohashi, Yoshiyuki Ohyama, Kouki Taniyama (1994)
Revista Matemática de la Universidad Complutense de Madrid
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In this paper we estimate the crossing number of a flat vertex graph in 3-space in terms of the reduced degree of its Yamada polynomial.
Luigi Grasselli, Michele Mulazzani (1999)
Disertaciones Matemáticas del Seminario de Matemáticas Fundamentales
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P. Cristofori, C. Gagliardi, L. Grasselli (1995)
Revista Matemática de la Universidad Complutense de Madrid
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By means of branched coverings techniques, we prove that the Heegaard genus and the regular genus of an orientable 3-manifold with boundary coincide.
H. M. Hilden, J. M. Montesinos, D. M. Tejada, M. M. Toro (2004)
Disertaciones Matemáticas del Seminario de Matemáticas Fundamentales
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K. Motegi (1996)
Revista Matemática de la Universidad Complutense de Madrid
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Let K (resp. L) be a Montesinos knot (resp. link) with at least four branches. Then we show the unknotting number (resp. unlinking number) of K (resp. L) is greater than 1.
José María Montesinos-Amilibia (2003)
Revista Matemática Complutense
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In this paper, a representation of closed 3-manifolds as branched coverings of the 3-sphere, proved in [13], and showing a relationship between open 3-manifolds and wild knots and arcs will be illustrated by examples. It will be shown that there exist a 3-fold simple covering p : S --> S branched over the remarkable simple closed curve of Fox [4] (a wild knot). Moves are defined such that when applied to a branching set, the corresponding covering manifold remains unchanged, while...