Multicurves and Equivariant Cohomology

Multicurves and Equivariant Cohomology PDF Author: Neil P. Strickland
Publisher: American Mathematical Soc.
ISBN: 0821849018
Category : Mathematics
Languages : en
Pages : 130

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Book Description
Let $A$ be a finite abelian group. The author sets up an algebraic framework for studying $A$-equivariant complex-orientable cohomology theories in terms of a suitable kind of equivariant formal group. He computes the equivariant cohomology of many spaces in these terms, including projective bundles (and associated Gysin maps), Thom spaces, and infinite Grassmannians.

Multicurves and Equivariant Cohomology

Multicurves and Equivariant Cohomology PDF Author: Neil P. Strickland
Publisher: American Mathematical Soc.
ISBN: 0821849018
Category : Mathematics
Languages : en
Pages : 130

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Book Description
Let $A$ be a finite abelian group. The author sets up an algebraic framework for studying $A$-equivariant complex-orientable cohomology theories in terms of a suitable kind of equivariant formal group. He computes the equivariant cohomology of many spaces in these terms, including projective bundles (and associated Gysin maps), Thom spaces, and infinite Grassmannians.

On the Algebraic Foundations of Bounded Cohomology

On the Algebraic Foundations of Bounded Cohomology PDF Author: Theo Bühler
Publisher: American Mathematical Soc.
ISBN: 0821853112
Category : Mathematics
Languages : en
Pages : 126

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Book Description
It is a widespread opinion among experts that (continuous) bounded cohomology cannot be interpreted as a derived functor and that triangulated methods break down. The author proves that this is wrong. He uses the formalism of exact categories and their derived categories in order to construct a classical derived functor on the category of Banach $G$-modules with values in Waelbroeck's abelian category. This gives us an axiomatic characterization of this theory for free, and it is a simple matter to reconstruct the classical semi-normed cohomology spaces out of Waelbroeck's category. The author proves that the derived categories of right bounded and of left bounded complexes of Banach $G$-modules are equivalent to the derived category of two abelian categories (one for each boundedness condition), a consequence of the theory of abstract truncation and hearts of $t$-structures. Moreover, he proves that the derived categories of Banach $G$-modules can be constructed as the homotopy categories of model structures on the categories of chain complexes of Banach $G$-modules, thus proving that the theory fits into yet another standard framework of homological and homotopical algebra.

Vector Bundles on Degenerations of Elliptic Curves and Yang-Baxter Equations

Vector Bundles on Degenerations of Elliptic Curves and Yang-Baxter Equations PDF Author: Igor Burban
Publisher: American Mathematical Soc.
ISBN: 0821872923
Category : Mathematics
Languages : en
Pages : 144

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Book Description
"November 2012, volume 220, number 1035 (third of 4 numbers)."

A Theory of Generalized Donaldson-Thomas Invariants

A Theory of Generalized Donaldson-Thomas Invariants PDF Author: Dominic D. Joyce
Publisher: American Mathematical Soc.
ISBN: 0821852795
Category : Mathematics
Languages : en
Pages : 212

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Book Description
This book studies generalized Donaldson-Thomas invariants $\bar{DT}{}^\alpha(\tau)$. They are rational numbers which `count' both $\tau$-stable and $\tau$-semistable coherent sheaves with Chern character $\alpha$ on $X$; strictly $\tau$-semistable sheaves must be counted with complicated rational weights. The $\bar{DT}{}^\alpha(\tau)$ are defined for all classes $\alpha$, and are equal to $DT^\alpha(\tau)$ when it is defined. They are unchanged under deformations of $X$, and transform by a wall-crossing formula under change of stability condition $\tau$. To prove all this, the authors study the local structure of the moduli stack $\mathfrak M$ of coherent sheaves on $X$. They show that an atlas for $\mathfrak M$ may be written locally as $\mathrm{Crit}(f)$ for $f:U\to{\mathbb C}$ holomorphic and $U$ smooth, and use this to deduce identities on the Behrend function $\nu_\mathfrak M$. They compute the invariants $\bar{DT}{}^\alpha(\tau)$ in examples, and make a conjecture about their integrality properties. They also extend the theory to abelian categories $\mathrm{mod}$-$\mathbb{C}Q\backslash I$ of representations of a quiver $Q$ with relations $I$ coming from a superpotential $W$ on $Q$.

General Relativistic Self-Similar Waves that Induce an Anomalous Acceleration into the Standard Model of Cosmology

General Relativistic Self-Similar Waves that Induce an Anomalous Acceleration into the Standard Model of Cosmology PDF Author: Joel Smoller
Publisher: American Mathematical Soc.
ISBN: 0821853589
Category : Science
Languages : en
Pages : 82

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Book Description
The authors prove that the Einstein equations for a spherically symmetric spacetime in Standard Schwarzschild Coordinates (SSC) close to form a system of three ordinary differential equations for a family of self-similar expansion waves, and the critical ($k=0$) Friedmann universe associated with the pure radiation phase of the Standard Model of Cosmology is embedded as a single point in this family. Removing a scaling law and imposing regularity at the center, they prove that the family reduces to an implicitly defined one-parameter family of distinct spacetimes determined by the value of a new acceleration parameter $a$, such that $a=1$ corresponds to the Standard Model. The authors prove that all of the self-similar spacetimes in the family are distinct from the non-critical $k\neq0$ Friedmann spacetimes, thereby characterizing the critical $k=0$ Friedmann universe as the unique spacetime lying at the intersection of these two one-parameter families. They then present a mathematically rigorous analysis of solutions near the singular point at the center, deriving the expansion of solutions up to fourth order in the fractional distance to the Hubble Length. Finally, they use these rigorous estimates to calculate the exact leading order quadratic and cubic corrections to the redshift vs luminosity relation for an observer at the center.

On $L$-Packets for Inner Forms of $SL_n$

On $L$-Packets for Inner Forms of $SL_n$ PDF Author: Kaoru Hiraga
Publisher: American Mathematical Soc.
ISBN: 0821853643
Category : Mathematics
Languages : en
Pages : 110

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Book Description
The theory of $L$-indistinguishability for inner forms of $SL_2$ has been established in the well-known paper of Labesse and Langlands (L-indistinguishability forSL$(2)$. Canad. J. Math. 31 (1979), no. 4, 726-785). In this memoir, the authors study $L$-indistinguishability for inner forms of $SL_n$ for general $n$. Following the idea of Vogan in (The local Langlands conjecture. Representation theory of groups and algebras, 305-379, Contemp. Math. 145 (1993)), they modify the $S$-group and show that such an $S$-group fits well in the theory of endoscopy for inner forms of $SL_n$.

The Lin-Ni's Problem for Mean Convex Domains

The Lin-Ni's Problem for Mean Convex Domains PDF Author: Olivier Druet
Publisher: American Mathematical Soc.
ISBN: 0821869094
Category : Mathematics
Languages : en
Pages : 118

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Book Description
The authors prove some refined asymptotic estimates for positive blow-up solutions to $\Delta u+\epsilon u=n(n-2)u^{\frac{n+2}{n-2}}$ on $\Omega$, $\partial_\nu u=0$ on $\partial\Omega$, $\Omega$ being a smooth bounded domain of $\mathbb{R}^n$, $n\geq 3$. In particular, they show that concentration can occur only on boundary points with nonpositive mean curvature when $n=3$ or $n\geq 7$. As a direct consequence, they prove the validity of the Lin-Ni's conjecture in dimension $n=3$ and $n\geq 7$ for mean convex domains and with bounded energy. Recent examples by Wang-Wei-Yan show that the bound on the energy is a necessary condition.

On First and Second Order Planar Elliptic Equations with Degeneracies

On First and Second Order Planar Elliptic Equations with Degeneracies PDF Author: Abdelhamid Meziani
Publisher: American Mathematical Soc.
ISBN: 0821853120
Category : Mathematics
Languages : en
Pages : 90

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Book Description
This paper deals with elliptic equations in the plane with degeneracies. The equations are generated by a complex vector field that is elliptic everywhere except along a simple closed curve. Kernels for these equations are constructed. Properties of solutions, in a neighborhood of the degeneracy curve, are obtained through integral and series representations. An application to a second order elliptic equation with a punctual singularity is given.

Second Order Analysis on $(\mathscr {P}_2(M),W_2)$

Second Order Analysis on $(\mathscr {P}_2(M),W_2)$ PDF Author: Nicola Gigli
Publisher: American Mathematical Soc.
ISBN: 0821853090
Category : Mathematics
Languages : en
Pages : 173

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Book Description
The author develops a rigorous second order analysis on the space of probability measures on a Riemannian manifold endowed with the quadratic optimal transport distance $W_2$. The discussion includes: definition of covariant derivative, discussion of the problem of existence of parallel transport, calculus of the Riemannian curvature tensor, differentiability of the exponential map and existence of Jacobi fields. This approach does not require any smoothness assumption on the measures considered.

Towards a Modulo $p$ Langlands Correspondence for GL$_2$

Towards a Modulo $p$ Langlands Correspondence for GL$_2$ PDF Author: Christophe Breuil
Publisher: American Mathematical Soc.
ISBN: 0821852272
Category : Mathematics
Languages : en
Pages : 127

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Book Description
The authors construct new families of smooth admissible $\overline{\mathbb{F}}_p$-representations of $\mathrm{GL}_2(F)$, where $F$ is a finite extension of $\mathbb{Q}_p$. When $F$ is unramified, these representations have the $\mathrm{GL}_2({\mathcal O}_F)$-socle predicted by the recent generalizations of Serre's modularity conjecture. The authors' motivation is a hypothetical mod $p$ Langlands correspondence.