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- Insecurity is generic in a conformal class of Riemannian metrics — Department of Mathematics and Computer Science

Students Info Insecurity is generic in a conformal class of Riemannian metrics filed under Topology Seminar James Hebda Saint Louis University What Topology Seminar When Fri Nov 16 2012 from 11 00 AM to 11 50 AM Where Ritter Hall 316 Add event to calendar vCal iCal Abstract A pair of points x y in a Riemannian manifold M g is said to be secure if there exists a finite set of points intercepting every geodesic segment joining x to y Given any conformal equivalence class C of Riemannian metrics on a closed manifold M of dimension at least two and given any pair of points x y in M there exists a dense G δ set C C such that x and y are not secure for every metric g in C Document Actions iCalendar vCalendar Send this Print this Subscribe to Talklist Sign up here for a weekly email of upcoming department events Email address Your name February 2016 February Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Upcoming Events

Original URL path: http://mathcs.slu.edu/seminars/topology-seminar/old-seminars/insecurity-is-generic-in-a-conformal-class-of-riemannian-metrics (2016-02-12)

Open archived version from archive - Finite Group Actions on Prism Manifolds — Department of Mathematics and Computer Science

Kalliongis Saint Louis University What Topology Seminar When Fri Nov 09 2012 from 11 00 AM to 11 50 AM Where Ritter Hall 316 Add event to calendar vCal iCal Continued from last week Abstract I will begin by defining a prism manifold M and the two ways that such a manifold can be S1 fibered These manifolds have an imbeddded Heegaard Klein bottle We consider the classification up to equivalence of all finite group actions which operate on M and preserve a Heegaard Klein bottle K These actions are completely determined by their restrictions to K and any such action is found to be isomorphic to either Zm Z2 Z2m Dih Zm or Dih Z2 Z2m In addition we will consider fiber preserving actions and the question of when such actions leave a Heegaard Klein bottle invariant Document Actions iCalendar vCalendar Send this Print this Subscribe to Talklist Sign up here for a weekly email of upcoming department events Email address Your name February 2016 February Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

Original URL path: http://mathcs.slu.edu/seminars/old-seminars/finite-group-actions-on-prism-manifolds-1 (2016-02-12)

Open archived version from archive - Finite Group Actions on Prism Manifolds — Department of Mathematics and Computer Science

Seminar John Kaliongis Saint Louis University What Topology Seminar When Fri Nov 02 2012 from 11 00 AM to 11 50 AM Where Ritter Hall 316 Add event to calendar vCal iCal Abstract I will begin by defining a prism manifold M and the two ways that such a manifold can be S1 fibered These manifolds have an imbeddded Heegaard Klein bottle We consider the classification up to equivalence of all finite group actions which operate on M and preserve a Heegaard Klein bottle K These actions are completely determined by their restrictions to K and any such action is found to be isomorphic to either Zm Z2 Z2m Dih Zm or Dih Z2 Z2m In addition we will consider fiber preserving actions and the question of when such actions leave a Heegaard Klein bottle invariant Document Actions iCalendar vCalendar Send this Print this Subscribe to Talklist Sign up here for a weekly email of upcoming department events Email address Your name February 2016 February Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Original URL path: http://mathcs.slu.edu/seminars/old-seminars/finite-group-actions-on-prism-manifolds (2016-02-12)

Open archived version from archive - Topological measures of similarity on curves — Department of Mathematics and Computer Science

Students Info Topological measures of similarity on curves filed under Topology Seminar Erin Chambers Saint Louis University What Topology Seminar When Fri Oct 26 2012 from 11 00 AM to 11 50 AM Add event to calendar vCal iCal Abstract The question of how to measure similarity between curves in various topological spaces has received much attention recently Possibilities for comparing curves include the Frechet distance and its variants such as geodesic homotopic and isotopic Frechet distance homotopy height and deformation area or the area of the homotopy many of these have algorithms in settings that range from the plane to combinatorial surfaces to cell complexes We will compare and survey known results as well as recent progress and open questions in several of these settings Document Actions iCalendar vCalendar Send this Print this Subscribe to Talklist Sign up here for a weekly email of upcoming department events Email address Your name February 2016 February Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Upcoming Events Geometry Topology Seminar Tue Feb 16 2016

Original URL path: http://mathcs.slu.edu/seminars/old-seminars/topological-measures-of-similarity-on-curves (2016-02-12)

Open archived version from archive - Curve Complex Analogues for Out(F_n) [Part III] — Department of Mathematics and Computer Science

to calendar vCal iCal Abstract The group Out F n of outer automorphisms of the free group has been an object of active study for many years yet its geometry is not well understood Recently effort has been focused on finding a hyperbolic complex on which Out F n acts in analogy with the curve complex for the mapping class group In this talk I will introduce these objects and discuss some results about the geometry of some proposed analogues I will focus on my joint work with Dmytro Savchuk on the geometry of the edge splitting graph or equivalently the separating sphere graph We give a characterization of geodesic paths in this graph and use our characterization to find lower bounds on distances between vertices Our distance calculations allow us to find quasiflats of arbitrary dimension Thus this graph is not hyperbolic and has infinite asymptotic dimension I am planning on going slowly and giving definitions of unfamiliar concepts so this will probably be a series of two talks Document Actions iCalendar vCalendar Send this Print this Subscribe to Talklist Sign up here for a weekly email of upcoming department events Email address Your name February 2016 February Su

Original URL path: http://mathcs.slu.edu/seminars/old-seminars/curve-complex-analogues-for-out-f_n-part-iii (2016-02-12)

Open archived version from archive - Curve Complex Analogues for Out(F_n) — Department of Mathematics and Computer Science

vCal iCal Abstract The group Out F n of outer automorphisms of the free group has been an object of active study for many years yet its geometry is not well understood Recently effort has been focused on finding a hyperbolic complex on which Out F n acts in analogy with the curve complex for the mapping class group In this talk I will introduce these objects and discuss some results about the geometry of some proposed analogues I will focus on my joint work with Dmytro Savchuk on the geometry of the edge splitting graph or equivalently the separating sphere graph We give a characterization of geodesic paths in this graph and use our characterization to find lower bounds on distances between vertices Our distance calculations allow us to find quasiflats of arbitrary dimension Thus this graph is not hyperbolic and has infinite asymptotic dimension I am planning on going slowly and giving definitions of unfamiliar concepts so this will probably be a series of two talks Document Actions iCalendar vCalendar Send this Print this Subscribe to Talklist Sign up here for a weekly email of upcoming department events Email address Your name February 2016 February Su Mo Tu

Original URL path: http://mathcs.slu.edu/seminars/old-seminars/curve-complex-analogues-for-out-f_n (2016-02-12)

Open archived version from archive - How to Walk Your Dog in the Mountains — Department of Mathematics and Computer Science

Topology Seminar Amir Nayyeri U of Illinois What Computer Science Seminar Topology Seminar When Tue Feb 07 2012 from 01 00 PM to 02 00 PM Where TBA Add event to calendar vCal iCal We describe a O log n approximation algorithm for computing the homotopic Frechet distance between two polygonal curves that lie on the boundary of a surface Prior to this work algorithms were known only for curves on the Euclidean plane with polygonal obstacles A key technical ingredient in our analysis is an O log n approximation algorithm for computing the minimum height of a homotopy between two curves No algorithms were previously known for approximating this parameter Surprisingly it is not even known if computing either the homotopic Frechet distance or the minimum height of a homotopy is in NP Joint work with Sariel Har Peled Mohammad Salavatipour and Anastasios Sidiropoulos Document Actions iCalendar vCalendar Send this Print this Subscribe to Talklist Sign up here for a weekly email of upcoming department events Email address Your name February 2016 February Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Original URL path: http://mathcs.slu.edu/seminars/computer-science-seminar/how-to-walk-your-dog-in-the-mountains (2016-02-12)

Open archived version from archive - The Jones-Kauffman Polynomial and the Bollob'as-Riordan Polynomial — Department of Mathematics and Computer Science

Riordan Polynomial filed under Colloquium Topology Seminar Dr Xian an Jin Xi amen University China What Colloquium Topology Seminar When Thu Oct 20 2011 from 01 00 PM to 02 00 PM Where Ritter Hall 30 Add event to calendar vCal iCal Abstract In this talk we first construct a signed ribbon graph for an arbitrary virtual link diagram based on its graphical checkerboard coloring and contractions for all twisted bands corresponding to virtual crossings Then we build a relation between the Kauffman bracket polynomial of a virtual link diagram and Bollob as Riordan polynomial of the signed ribbon graph described above Finally we prove that this relation is an extension of the famous result of Kauffman s hence Thistlethwaite s on the connection between the Kauffman bracket polynomial of classical link diagrams and the Tutte polynomial of corresponding signed checkerboard graphs Document Actions iCalendar vCalendar Send this Print this Subscribe to Talklist Sign up here for a weekly email of upcoming department events Email address Your name February 2016 February Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Original URL path: http://mathcs.slu.edu/seminars/topology-seminar/old-seminars/a-relationship-between-two-graphical-models-of-the-kauffman-polynomial (2016-02-12)

Open archived version from archive