Now showing items 1-10 of 41
Homology cobordism and Seifert fibered 3-manifolds
(American Mathematical Society, 2014)
It is known that every closed oriented 3-manifold is homology cobordant to a hyperbolic 3-manifold. By contrast we show that many homology cobordism classes contain no Seifert fibered 3-manifold. This is accomplished by ...
Wigner-von Neumann type perturbations of periodic Schrödinger operators
(American Mathematical Society, 2015)
Schrödinger operators on the half line. More precisely, the perturbations we consider satisfy a generalized bounded variation condition at infinity and an LP decay condition. We show that the absolutely continuous spectrum ...
New Anomalous Lieb-Robinson Bounds in Quasiperiodic XY Chains
(American Physical Society, 2014)
We announce and sketch the rigorous proof of a new kind of anomalous (or sub-ballistic) Lieb-Robinson (LR) bound for an isotropic XY chain in a quasiperiodic transversal magnetic field. Instead of the usual effective light ...
Cubic fourfolds containing a plane and a quantic del Pezzo surface
(Foundation Compositio Mathematica, 2014)
We isolate a class of smooth rational cubic fourfolds X containing a plane whose associated quadric surface bundle does not have a rational section. This is equivalent to the nontriviality of the Brauer class β of the even ...
The second rational homology group of the moduli space of curves with level structures
Let Γ be a finite-index subgroup of the mapping class group of a closed genus g surface that contains the Torelli group. For instance, Γ can be the level L subgroup or the spin mapping class group. We show that H2(Γ;Q) ∼= Q ...
Higher-Order Signature Cocycles for Subgroups of Mapping Class Groups and Homology Cylinders
(Oxford University Press, 2012)
The Picard group of the moduli space of curves with level structures
For 4 - L and g large, we calculate the integral Picard groups of the moduli spaces of curves and principally polarized abelian varieties with level L structures. In particular, we determine the divisibility properties of ...
Generators for the hyperelliptic Torelli group and the kernel of the Burau representation at t=−1
We prove that the hyperelliptic Torelli group is generated by Dehn twists about separating curves that are preserved by the hyperelliptic involution. This verifies a conjecture of Hain. The hyperelliptic Torelli group can ...
Dichotomy for arithmetic progressions in subsets of reals
(American Mathematical Society, 2016)
Let H stand for the set of homeomorphisms φ:[0, 1] → [0, 1]. We prove the following dichotomy for Borel subsets A ⊂ [0, 1]: • either there exists a homeomorphism φ ∈ Hsuch that the image φ(A) contains no 3-term arithmetic ...