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A locally-built, LLM-digested index of recent arXiv papers in quant finance, geometry/topology, and statistical ML — keyword search served straight from SQLite on this machine.

168,694 papers · 148 categories

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48 results for stably almost complex

Explicit formulas for Hattori-Stong integrability conditions and manifolds' signature properties.

problem Understanding and calculating the signature of stably almost-complex manifolds.
method Combinatorial techniques to derive explicit formulas for Chern class coefficients and signature conditions.
result An evenness condition for the signature of stably almost-complex manifolds in terms of Chern numbers.

We complete our recent classification of compact inner symmetric spaces with weakly complex tangent bundle by filling up a case which was left open, and extend this classification to the larger category of compact homogeneous spaces with positive Euler characteristic. We show that a simply connected compact equal rank …

2012-02-15abs ↗pdf ↗

We show that the Cappell-Shaneson version of Pick's theorem for simple lattice polytopes is a consequence of a general relation between characteristic numbers of virtual submanifolds dual to the characteristic classes of a stably almost complex manifold. This relation is analogous to the miraculous cancellation formula…

2007-10-03abs ↗pdf ↗

The study finds stably free modules and distinct 2-complexes for large ranks.

problem Classifying homotopically distinct 2-complexes with specific fundamental groups and Euler characteristics.
method Using stably free modules and group theory, the study constructs and classifies 2-complexes.
result The existence of homotopically distinct 2-complexes with specific properties for all k2k \ge 2.

New invariant detects non-homotopy equivalent 4-manifolds.

problem Detecting non-homotopy equivalent 4-manifolds.
method Extending Kreck and Schafer's doubling construction to 2-complexes with finite fundamental group.
result Existence of kk closed smooth 4-manifolds that are stably diffeomorphic but not homotopy equivalent.

The paper constructs infinitely many stably diffeomorphic but non-homotopy equivalent manifolds.

problem Realising modified surgery obstructions for stably diffeomorphic manifolds.
method Proving a realisation result for subsets of Kreck's modified surgery monoid.
result Infinitely many stably diffeomorphic but non-homotopy equivalent manifolds.

Characterizes stably elliptic elements in Lie groups and their properties.

problem Understanding stably elliptic elements in Lie groups and their geometric and algebraic properties.
method Characterization through fixed point algebra and Weyl group action; relates to maximal invariant cones and compactness of order intervals.
result Connected components of stably elliptic elements can be described using Weyl group action on a compactly embedded Cartan subalgebra.

We prove that if the circle group acts smooth and unitary on 2n-dimensional stably complex manifold with two isolated fixed points and it is not bound equivariantly, then n=1 or 3. Our proof relies on the rigid Hirzebruch genera.

2015-12-11abs ↗pdf ↗

The monoids l_{2q+1}(Z[π]) detect s-cobordisms amongst certain bordisms between stably diffeomorphic 2q-dimensional manifolds and generalise the Wall simple surgery obstruction groups, L_{2q+1}^s(Z[π]) \subset l_{2q+1}(Z[π]). In this paper we give exact sequences which completely describe l_{2q+1}(Z[π]) as a set and wh…

2008-08-14abs ↗pdf ↗

The paper classifies Poincaré complexes as topological manifolds.

problem Classifying Poincaré complexes as topological manifolds.
method Using spherical fibrations and CW-complexes, the paper proves stability and homotopy equivalence.
result A sufficient condition for Poincaré complexes to be homotopy types of topological manifolds.

The mapping class group of a closed surface of genus gg is an extension of the Torelli group by the symplectic group. This leads to two natural problems: (a) compute (stably) the symplectic decomposition of the lower central series of the Torelli group and (b) compute (stably) the Poincaré polynomial of the cohomology…

2017-12-10abs ↗pdf ↗

We give complete geometric invariants of cobordisms of fold maps with oriented singular set and cobordisms of even codimensional fold maps. These invariants are given in terms of cobordisms of stably framed manifolds and cobordisms of immersions with prescribed normal bundles defined by the author in his earlier works.

2008-03-11abs ↗pdf ↗

The paper defines a Chern-Simons invariant for stably trivial vector bundles and uses it to obstruct conformal immersions.

problem Obstructing conformal immersions of Riemannian manifolds.
method Defining a Chern-Simons invariant for stably trivial vector bundles and using it to derive an obstruction.
result An obstruction for conformally immersing a n-dimensional Riemannian manifold in a translation manifold of dimension n+1.

The notion of a (stably) decomposable fiber bundle is introduced. In low dimensions, for torus fiber bundles over a circle the notion translates into a property of elements of the special linear group of integral matrices. We give a complete characterization of the stably decomposable torus fiber bundle of fiber-dimens…

2016-07-25abs ↗pdf ↗

The first result is the semicontinuity of automorphism groups for the collection of complex two-dimensional bounded pseudoconvex domains with smooth boundary of finite D'Angelo type. The method of proof is new so that it simplifies the previous proof of earlier semicontinuity theorems on bounded strongly pseudoconvex d…

2013-06-14abs ↗pdf ↗

The paper combines several fortunate mini miracles to achieve its two objectives. These were woven together in a several year's effort to answer a question raised by Iz Singer a decade ago. Our answer is accessible to the topologist, to the differential geometer and to the analyst who appreciates the statement of the I…

2018-03-19abs ↗pdf ↗

Is a given map between compact topological manifolds homotopic to the projection map of a fiber bundle? In this paper obstructions to this question are introduced with values in higher algebraic K-theory. Their vanishing implies that the given map fibers stably. The methods also provide results for the corresponding un…

2011-05-24abs ↗pdf ↗

We study closed, oriented 4-manifolds whose fundamental group is that of a closed, oriented, aspherical 3-manifold. We show that two such 4-manifolds are stably diffeomorphic if and only if they have the same w_2-type and their equivariant intersection forms are stably isometric. We also find explicit algebraic invaria…

2015-11-04abs ↗pdf ↗

Stable unactivated neurons reduce expressiveness in ReLU networks.

problem Reducing expressiveness in ReLU neural networks due to stably unactivated neurons.
method Investigated the probability of neurons being stably unactivated in ReLU networks with symmetric weight and bias distributions.
result Proved the probability of a neuron being stably unactivated in the second hidden layer of a ReLU network.

The paper verifies stable handleslide triviality of some R-links and shows many are stably equivalent.

problem Stable handleslide triviality of R-links as potential counterexamples to the generalized property R conjecture.
method Implemented an algorithm to construct all R-links explicitly and verified their stable handleslide triviality.
result Many R-links are stably handleslide equivalent.

The paper defines and constructs almost complex blow-ups on 4D almost complex manifolds.

problem Existence and uniqueness of almost complex blow-ups on almost complex manifolds.
method Definition and construction of almost complex blow-ups, proving their existence and uniqueness.
result Existence and uniqueness of almost complex blow-ups on 4D almost complex manifolds.

We develop a theory of chain complex double-cobordism for chain complexes equipped with Poincaré duality. The resulting double-cobordism groups are a refinement of Ranicki's torsion algebraic LL-groups for localisations of a commutative ring with involution. The refinement is analogous to the difference between metabo…

2015-08-05abs ↗pdf ↗

Stable cubulations and bicombings in mapping class groups and Teichmüller spaces.

problem Understanding geometric structures in mapping class groups and Teichmüller spaces.
method Proving stably approximated by CAT(0) cube complexes, applying to broader colorable hierarchically hyperbolic spaces and groups.
result Stable cubulations and bicombings in mapping class groups and Teichmüller spaces, with stable coarse barycenters.

Harmonic almost complex structures on specific Lie groups and solvmanifolds identified.

problem Characterizing harmonic almost complex structures on almost abelian Lie groups and solvmanifolds.
method Adapted Gray-Hervella classification to almost abelian Lie groups, characterized harmonic structures.
result Examples of harmonic almost complex structures in different Gray-Hervella classes on compact almost abelian solvmanifolds.

Study shows almost complex structures with certain tensor properties are prevalent.

problem Characterizing almost complex structures with specific tensor properties.
method Analyzes the space of almost complex structures on compact manifolds.
result The space of almost complex structures with rank at least k Nijenhuis tensor is either empty or dense in each component.

Study stable equivalence relations on 4-manifolds, proving homotopy equivalent manifolds with abelian fundamental group are stably diffeomorphic.

problem Classifying stable equivalence relations on 4-manifolds.
method Combination of modified and classical surgery, focusing on homotopy equivalence up to stabilisation.
result Closed oriented homotopy equivalent 4-manifolds with abelian fundamental group are stably diffeomorphic.

We develop a new approach to the existence of time functions on Lorentzian manifolds, based on Conley's work regarding Lyapunov functions for dynamical systems. We recover Hawking's result that a stably causal admits a time function through a more general result giving the existence of a continuous function that is non…

2016-03-22abs ↗pdf ↗

Study on biharmonic almost complex structures on compact manifolds.

problem Existence and regularity of biharmonic almost complex structures.
method Analyzes biharmonic almost complex structures on compact almost Hermitian manifolds, focusing on dimension four.
result Existence of energy-minimizing biharmonic almost complex structures for various topologies and homotopy classes.