Deformations and transversality of pseudo-holomorphic discs

We prove analogs of Thom’s transversality theorem and Whitney’s theorem on immersions for pseudo-holomorphic discs. We also prove that pseudoholomorphic discs form a Banach manifold.     

Intertwining the geodesic flow and the Schr?dinger group on hyperbolic surfaces

We construct an explicit intertwining operator L{\mathcal L} between the Schr?dinger group e^{it \frac\triangle2}{e^{it \frac\triangle2}} and the geodesic flow on certain Hilbert spaces of symbols on the cotangent bundle T*X _Γ of a compact hyperbolic surface X _Γ = Γ\D. We also define Γ-invariant eigendistributions of the geodesic flow PS_{j, k, nj,-nk}{PS_{j, k, \nu_j,-\nu_k}} (Patterson-Sullivan distributions) out of pairs of \triangle{\triangle} -eigenfunctions, generalizing the diagonal case j = k treated in Anantharaman and Zelditch (Ann. Henri Poincaré 8(2):361–426, 2007). The operator L{\mathcal L} maps PS_{j, k, nj,-nk}{PS_{j, k, \nu_j,-\nu_k}} to the Wigner distribution W^G_j,k{W^{\Gamma}_{j,k}} studied in quantum chaos. We define Hilbert spaces H_PS{\mathcal H_{PS}} (whose dual is spanned by {PS_{j, k, nj,-nk}{PS_{j, k, \nu_j,-\nu_k}}}), resp. H_W{\mathcal H_W} (whose dual is spanned by {W^G_j,k}{\{W^{\Gamma}_{j,k}\}}), and show that L{\mathcal L} is a unitary isomorphism from H_W ? H_PS.{\mathcal H_{W} \to \mathcal H_{PS}.}     

Second moments of twisted Koecher-Maass series

Imai considered the twisted Koecher-Maass series for Siegel cusp forms of degree?2, twisted by Maass cusp forms and Eisenstein series, and used them to prove the converse theorem for Siegel modular forms. They do not have Euler products, and it is not even known whether they converge absolutely for Re(s)>1. Hence the standard convexity arguments do not apply to give bounds. In this paper, we obtain the average version of the second moments of the twisted Koecher-Maass series, using Titchmarsh??s method of Mellin inversion. When the Siegel modular form is a Saito Kurokawa lift of some half integral weight modular form, a theorem of Duke and Imamoglu says that the twisted Koecher Maass series is the Rankin-Selberg L-function of the half-integral weight form and Maass form of weight?1/2. Hence as a corollary, we obtain the average version of the second moment result for the Rankin-Selberg L-functions attached to half integral weight forms.     

Reverse estimates in growth spaces

Let H(B _d ) denote the space of holomorphic functions on the unit ball B _d of ${{\mathbb{C}}^d}$ . Given a radial doubling weight w, we construct functions ${f, g\in H(B_1)}$ such that |f| + |g| is comparable to w. Also, we obtain similar results for B _d , d ≥ 2, and for circular, strictly convex domains with smooth boundary. As an application, we study weighted composition operators and related integral operators on growth spaces of holomorphic functions.     

On the Adams–Riemann–Roch theorem in positive characteristic

Let p > 0 be a prime number. We give a short proof of the Adams–Riemann–Roch theorem for the p-th Adams operation, when the involved schemes live in characteristic p. We also answer a question of B. Köck.     

Gibbs/Metropolis algorithms on a convex polytope

This paper gives sharp rates of convergence for natural versions of the Metropolis algorithm for sampling from the uniform distribution on a convex polytope. The singular proposal distribution, based on a walk moving locally in one of a fixed, finite set of directions, needs some new tools. We get useful bounds on the spectrum and eigenfunctions using Nash and Weyl-type inequalities. The top eigenvalues of the Markov chain are closely related to the Neumann eigenvalues of the polytope for a novel Laplacian.     

Every ordinary differential equation with a strict Lyapunov function is a gradient system

We explain and prove the statement from the title. This allows us to formulate a new type of gradient inequality and to obtain a new stabilization result for gradient-like ordinary differential equations.     

Exponential decay of the power spectrum and finite dimensionality for solutions of the three dimensional primitive equations

In this article we estimate the number of modes, volumes and nodes, sufficient to describe well the solution of the three dimensional primitive equations; the physical meaning of these estimates is also discussed. We also study the exponential decay of the spatial power spectrum for the three dimensional primitive equations.