|
| |
|
|
A156097
|
|
Number of rigid genus-2 bipartite crystallizations of orientable 3-manifolds with 2n vertices.
|
|
1
|
|
|
|
1, 2, 4, 6, 8, 14, 18, 23, 38, 47, 58, 79, 118, 128, 159
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
7,2
|
|
|
COMMENTS
|
This is the upper row of Table 1, p.9, of Bandieri, et al. There are no rigid genus two crystallizations with less than 14 vertices (i.e., with n = 7). Abstract: "We improve and extend to the non-orientable case a recent result of Karabas, Malicki and Nedela concerning the classification of all orientable prime 3-manifolds of Heegaard genus two, triangulated with at most 42 coloured tetrahedra." Karabas, Malicki and Nedela show that there exist exactly 78 non-homeomorphic, closed, orientable, prime 3-manifolds with Heegaard genus two, admitting a colored triangulation with at most 42 tetrahedra. Each manifold M is identified by a suitable 6-tuple of nonnegative integers, representing a minimal crystallization - hence a minimal colored triangulation - of M. From such a 6-tuple, a presentation of the fundamental group and of the first homology group of M are easily obtained.
|
|
|
REFERENCES
|
P. Bandieri et al., A census of genus-two 3-manifolds [with] up to 42 colored tetrahedra, Discrete Math., 310 (2010), 2469-2481.
|
|
|
LINKS
|
Table of n, a(n) for n=7..21.
Paola Bandieri, Paola Cristofori and Carlo Gagliardi, A census of genus two 3-manifolds up to 42 coloured tetrahedra, Feb 3, 2009.
J. Karabas, P. Malicky, R. Nedela, Three-manifolds with Heegaard genus at most two represented by crystallisations with at most 42 vertices, Discrete Math. 307 (2007), no. 21, 2569-2590.
|
|
|
CROSSREFS
|
Cf. A156098.
Sequence in context: A049015 A005250 A162762 * A288793 A039597 A317979
Adjacent sequences: A156094 A156095 A156096 * A156098 A156099 A156100
|
|
|
KEYWORD
|
nonn,more
|
|
|
AUTHOR
|
Jonathan Vos Post, Feb 04 2009
|
|
|
EXTENSIONS
|
Edited by N. J. A. Sloane, Sep 26 2010
|
|
|
STATUS
|
approved
|
| |
|
|
