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Mario Eudave-Muñoz

Publications and source records attributed to Mario Eudave-Muñoz.

9 recordsLinked to original sources

A Kuratowski-Type Classification of Critical Complexes for the 3-Sphere

We give a Kuratowski-type classification of a graph-defined class of minimal piecewise-linear obstructions to embeddability in the 3-sphere. A finite simplicial complex \(X\) is called critical for \(S^3\) if \(|X|\) does not embed in \(S^3\), whereas deleting the open star of any simplex in the second barycentric subdivision of \(X\) yields a polyhedron embeddable in \(S^3\). The main theorem completely classifies critical complexes of the form \((G\times S^1)\cup H\), where \(G\) and \(H\) are graphs and \(H\) is attached along vertices of the branch set of \(G\times S^1\). We prove that there are exactly seven such complexes up to homeomorphism: two \(K_4\)-type complexes, four \(Θ_4\)-type complexes, and one \(K_{2,3}\)-type complex. The proof is combinatorial in nature. By collapsing the \(S^1\)-factor of \(G\times S^1\), we associate to \(X\) a reduction graph \(\widehat X=G\cup H\). Criticality implies that \(H\) is a forest, \(G\) is planar, and \(\widehat X\) is inclusion-minimal non-planar. Kuratowski's theorem therefore reduces the classification to the cases \(K_5\) and \(K_{3,3}\). A finite analysis of forest attachments, together with a face-incidence criterion for embeddability, leaves precisely the seven models listed above. We also prove that every non-embeddable regular multibranched surface in \(S^3\) contains a critical subcomplex of the form \(M\cup H\), where \(M\) is a regular multibranched surface and \(H\) is a graph.

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Positive Artin Presentations

An integral framed, closed pure n-braid B' in the 3-sphere describes a positive Artin presentation, if the braid B can be put on a disk with holes such that each relation describes a positive path and these paths are disjoint. In the present paper we classify the closed, pure n-braids B' in the 3-sphere, such that B represents a positive Artin presentation. Also we prove that if such B describes a positive Artin presentation then B' is strongly invertible. Such positive Artin presentation give us the fundamental group of closed, connected and orientable 3-manifolds M, and in fact, by giving an example, we show that there exist 3-manifolds whose fundamental group does not admit a positive Artin presentation.

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On the transient number of a knot

The transient number of a knot K, denoted tr(K), is the minimal number of simple arcs that have to be attached to K, in order that K can be homotoped to a trivial knot in a regular neighborhood of the union of K and the arcs. We give a lower bound for tr(K) in terms of the rank of the first homology group of the double branched cover of K. In particular, if t(K)=1, then the first homology group of the double branched cover of K is cyclic. Using this, we can calculate the transient number of many knots in the tables and show that there are knots with arbitrarily large transient number.

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On non almost-fibered knots

An almost-fibered knot is a knot whose complement possesses a circular thin position in which there is one and only one weakly incompressible Seifert surface and one incompressible Seifert surface. Infinite examples of almost-fibered knots are known. In this article, we show the existence of infinitely many hyperbolic genus one knots that are not almost-fibered.

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Satellite knots and trivializing bands

We show an infinite family of satellite knots that can be unknotted by a single band move, but such that there is no band unknotting the knots which is disjoint from the satellite torus.

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Classification of genus two knots which admit a (1,1) decomposition

We describe the genus two knots which admit a genus one, one bridge position. These are divided into several families, one consists of vertical bandings of two genus one $(1,1)$-knots, other consists of vertical bandings of two cross cap number two 2-bridge knots, and the last one consists of genus two tunnel number one satellite knots.

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Nonhyperbolic Dehn fillings on hyperbolic 3-manifolds

We give three infinite families of examples of nonhyperbolic Dehn fillings on hyperbolic manifolds. A manifold in the first family admits two Dehn fillings of distance two apart, one of which is toroidal and annular, and the other is reducible and $\partial$-reducible. A manifold in the second family has boundary consisting of two tori, and admits two reducible Dehn fillings. A manifold in the third family admits a toroidal filling and a reducible filling with distance 3 apart. These examples establish the virtual bounds for distances between certain types of nonhyperbolic Dehn fillings.

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