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Morita cohomology
(University of CambridgeDepartment of Pure Mathematics and Mathematical Statistics, 2014-01-07)
This work constructs and compares different kinds of categorified cohomology of a locally contractible topological space X. Fix a commutative ring k of characteristic 0 and also denote by k the differential graded category ...
A 3-manifold group which is not four dimensional linear
(ElsevierJournal of Pure and Applied Algebra, 2014-01-28)
We give examples of closed orientable graph 3-manifolds having a fundamental group which is not a subgroup of GL(4, F) for any field F. This answers a question in the Kirby problem list from 1977 which is credited to the ...
Excitations in superfluids of atoms and polaritons
(University of CambridgeDepartment of Pure Mathematics and Mathematical StatisticsSt. Edmund's College, 2014-11-11)
This thesis is devoted to the study of excitations in atomic and polariton Bose-Einstein condensates (BEC). These two specimens are prime examples for equilibrium and non equilibrium BEC. The corresponding condensate wave ...
Random Intersection Trees
(JMLRJournal of Machine Learning Research, 2014-02)
Finding interactions between variables in large and high-dimensional datasets is often a serious computational challenge. Most approaches build up interaction sets incrementally, adding variables in a greedy fashion. The ...
Estimate nothing
(Taylor & FrancisQuantitative Finance, 2014)
In the econometrics of financial time series, it is customary to take some parametric model for the data, and then estimate the parameters from historical data. This approach suffers from several problems. Firstly, how is ...
An explicit upper bound for the Helfgott delta in SL(2,p)
(ElsevierJournal of Algebra, 2014-09-23)
Helfgott proved that there exists a δ > 0 such that if S is a symmetric generating subset of SL(2, p)containing 1 then either S^3=SL(2, p)or |S^3| ≥|S|^1+ δ. It is known that δ ≥ 1/3024. Here we show that δ ≤ (log_2 (7) ...
Investing and stopping
(Applied Probability TrustJournal of Applied Probability, 2014)
In this paper we solve the hedge fund manager’s optimization problem in a model that allows for investors to enter and leave the fund over time depending on its performance. The manager’s payoff at the end of the year will ...
Quadratic differentials as stability conditions
(SpringerPublications mathématiques de l'IHÉS, 2014)
We prove that moduli spaces of meromorphic quadratic differentials with simple zeroes on compact Riemann surfaces can be identified with spaces of stability conditions on a class of CY3 triangulated categories defined using ...
Quadratic differentials as stability conditions
(SpringerPublications mathématiques de l'IHÉS, 2014)
We prove that moduli spaces of meromorphic quadratic differentials with simple zeroes on compact Riemann surfaces can be identified with spaces of stability conditions on a class of CY3 triangulated categories defined using ...
A Symplectic Prolegomenon
(American Mathematical SocietyBulletin of the American Mathematical Society, 2014)
A symplectic manifold gives rise to a triangulated A∞-category, the derived Fukaya category, which encodes information on Lagrangian submanifolds and dynamics as probed by Floer cohomology. This survey aims to give some ...