A Total Whitehead Torsion Obstruction to Fibering over the Circle.
A TQFT for Wormhole cobordisms over the field of rational functions
We consider a cobordism category whose morphisms are punctured connected sums of ’s (wormhole spaces) with embedded admissibly colored banded trivalent graphs. We define a TQFT on this cobordism category over the field of rational functions in an indeterminant A. For r large, we recover, by specializing A to a primitive 4rth root of unity, the Witten-Reshetikhin-Turaev TQFT restricted to links in wormhole spaces. Thus, for r large, the rth Witten-Reshetikhin-Turaev invariant of a link in some wormhole...
A trace-class rigidity theorem for Kleinian groups.
A Transfer Homomorphism for Compact Lie Group Actions.
A twisted dimer model for knots
We develop a dimer model for the Alexander polynomial of a knot. This recovers Kauffman's state sum model for the Alexander polynomial using the language of dimers. By providing some additional structure we are able to extend this model to give a state sum formula for the twisted Alexander polynomial of a knot depending on a representation of the knot group.
A type of non-equivalent pseudogroups. Application to foliations
A topological result for non-Hausdorff spaces is proved and used to obtain a non-equivalence theorem for pseudogroups of local transformations. This theorem is applied to the holonomy pseudogroup of foliations.
A uniform approach to complexes arising from forests.
A uniformly quasiconformal group not isomorphic to a Möbius group.
A unique factorization theorem for countable products of circles
A universal bound for surfaces in 3-manifolds with a given Heegaard genus.
A universal class of 4-colored graphs.
A universal space for normal bundles of n-manifolds.
A user's guide to discrete Morse theory.
A Vanishing Theorem for Euler Characteristics.
A vanishing theorem for twisted Alexander polynomials with applications to symplectic 4-manifolds
In this paper we show that given any 3-manifold and any non-fibered class in there exists a representation such that the corresponding twisted Alexander polynomial is zero. We obtain this result by extending earlier work of ours and by combining this with recent results of Agol and Wise on separability of 3-manifold groups. This result allows us to completely classify symplectic 4-manifolds with a free circle action, and to determine their symplectic cones.
A very short proof of Forester's rigidity result.
A volume form on the SU(2)-representation space of knot groups.
A volume-preserving counterexample to the Seifert conjecture.
A weak regularity theorem for real analytic optimal control problems.
We consider real analytic finite-dimensional control problems with a scalar input that enters linearly in the evolution equations. We prove that, whenever it is possible to steer a state x to another state y by means of a measurable control, then it is possible to steer x to y by means of a control that has an extra regularity property, namely, that of being analytic on an open dense subset of its interval of definition. Since open dense sets can have very small measure, this is a very weak property....
A weighted graph polynomial from chromatic invariants of knots
Motivated by the work of Chmutov, Duzhin and Lando on Vassiliev invariants, we define a polynomial on weighted graphs which contains as specialisations the weighted chromatic invariants but also contains many other classical invariants including the Tutte and matching polynomials. It also gives the symmetric function generalisation of the chromatic polynomial introduced by Stanley. We study its complexity and prove hardness results for very restricted classes of graphs.