Witte, Nikolaus (2007)
Foldable Triangulations.
Technische Universität Darmstadt
Dissertation, Erstveröffentlichung
Kurzbeschreibung (Abstract)
A simplicial d-complex is foldable if it is (d+1)-colorable in the graph theoretic sense. Such a coloring defines a non-degenerated simplicial map to the d-simplex, hence the name "foldable". Foldable simplicial complexes are sometimes referred to as being "balanced". We apply foldable simplicial complexes to obtain the following two results. Any closed oriented PL d-manifold is a branched cover of the d-sphere, but no restrictions on the number of sheets nor the topology of the branching set are known for d>4 in general. As for dimension four, Piergallini [Topology 34(3):497-508, 1995] proved that every closed oriented PL 4-manifold is a 4-fold branched cover of the 4-sphere branched over an immersed PL surface. This generalizes a long standing result by Hilden and Montesinos to dimension four. Izmestiev and Joswig [Adv. Geom. 3(2):191-225, 2003] gave a combinatorial equivalent of the Hilden and Montesinos result, constructing (fairly explicit) closed oriented combinatorial 3-manifolds as unfoldings of combinatorial 3-spheres. The construction of Izmestiev and Joswig is generalized and applied to the result of Piergallini, obtaining closed oriented combinatorial 4-manifolds as unfoldings of combinatorial 4-spheres. Foldable and regular triangulations of products of lattice polytopes are constructed from foldable and regular triangulations of the factors. It is known that foldable triangulations of polytopes have a bipartite dual graph. The (weighted) size difference of this bipartition is a lower bound for the number of real roots of certain sparse polynomial systems by recent results of Soprunova and Sottile [Adv. Math. 204(1):116-151, 2006]. Special attention is paid to the cube case.
Typ des Eintrags: | Dissertation | ||||
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Erschienen: | 2007 | ||||
Autor(en): | Witte, Nikolaus | ||||
Art des Eintrags: | Erstveröffentlichung | ||||
Titel: | Foldable Triangulations | ||||
Sprache: | Englisch | ||||
Referenten: | Joswig, Prof. Dr. Michael ; Ziegler, Prof. Günter M. | ||||
Berater: | Joswig, Prof. Dr. Michael | ||||
Publikationsjahr: | 23 Februar 2007 | ||||
Ort: | Darmstadt | ||||
Verlag: | Technische Universität | ||||
Kollation: | IV, 128 Seiten, Illustrationen | ||||
Datum der mündlichen Prüfung: | 7 Februar 2007 | ||||
URL / URN: | urn:nbn:de:tuda-tuprints-7881 | ||||
Zugehörige Links: | |||||
Kurzbeschreibung (Abstract): | A simplicial d-complex is foldable if it is (d+1)-colorable in the graph theoretic sense. Such a coloring defines a non-degenerated simplicial map to the d-simplex, hence the name "foldable". Foldable simplicial complexes are sometimes referred to as being "balanced". We apply foldable simplicial complexes to obtain the following two results. Any closed oriented PL d-manifold is a branched cover of the d-sphere, but no restrictions on the number of sheets nor the topology of the branching set are known for d>4 in general. As for dimension four, Piergallini [Topology 34(3):497-508, 1995] proved that every closed oriented PL 4-manifold is a 4-fold branched cover of the 4-sphere branched over an immersed PL surface. This generalizes a long standing result by Hilden and Montesinos to dimension four. Izmestiev and Joswig [Adv. Geom. 3(2):191-225, 2003] gave a combinatorial equivalent of the Hilden and Montesinos result, constructing (fairly explicit) closed oriented combinatorial 3-manifolds as unfoldings of combinatorial 3-spheres. The construction of Izmestiev and Joswig is generalized and applied to the result of Piergallini, obtaining closed oriented combinatorial 4-manifolds as unfoldings of combinatorial 4-spheres. Foldable and regular triangulations of products of lattice polytopes are constructed from foldable and regular triangulations of the factors. It is known that foldable triangulations of polytopes have a bipartite dual graph. The (weighted) size difference of this bipartition is a lower bound for the number of real roots of certain sparse polynomial systems by recent results of Soprunova and Sottile [Adv. Math. 204(1):116-151, 2006]. Special attention is paid to the cube case. |
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Alternatives oder übersetztes Abstract: |
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Freie Schlagworte: | geometric topology, construction of combinatorial manifolds, branched covering, regular triangulations of lattice polytopes, real roots of polynomial systems, triangulations of cubes, simplicial complex | ||||
Sachgruppe der Dewey Dezimalklassifikatin (DDC): | 500 Naturwissenschaften und Mathematik > 510 Mathematik | ||||
Fachbereich(e)/-gebiet(e): | 04 Fachbereich Mathematik 04 Fachbereich Mathematik > Optimierung 04 Fachbereich Mathematik > Optimierung > Discrete Optimization |
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Hinterlegungsdatum: | 17 Okt 2008 09:22 | ||||
Letzte Änderung: | 27 Jul 2023 10:58 | ||||
PPN: | |||||
Referenten: | Joswig, Prof. Dr. Michael ; Ziegler, Prof. Günter M. | ||||
Datum der mündlichen Prüfung / Verteidigung / mdl. Prüfung: | 7 Februar 2007 | ||||
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