Exponential ReLU DNN Expression of Holomorphic Maps in High Dimension

For a parameter dimension $$d\in {\mathbb {N}}$$ d ∈ N , we consider the approximation of many-parametric maps $$u: [-\,1,1]^d\rightarrow {\mathbb R}$$ u : [ - 1 , 1 ] d → R by deep ReLU neural networks. The input dimension d may possibly be large, and we assume quantitative control of the domain of holomorphy of u: i.e., u admits a holomorphic extension to a Bernstein polyellipse $${{\mathcal {E}}}_{\rho _1}\times \cdots \times {{\mathcal {E}}}_{\rho _d} \subset {\mathbb {C}}^d$$ E ρ 1 × ⋯ × E ρ d ⊂ C d of semiaxis sums $$\rho _i>1$$ ρ i > 1 containing $$[-\,1,1]^{d}$$ [ - 1 , 1 ] d . We establish the exponential rate $$O(\exp (-\,bN^{1/(d+1)}))$$ O ( exp ( - b N 1 / ( d + 1 ) ) ) of expressive power in terms of the total NN size N and of the input dimension d of the ReLU NN in $$W^{1,\infty }([-\,1,1]^d)$$ W 1 , ∞ ( [ - 1 , 1 ] d ) . The constant $$b>0$$ b > 0 depends on $$(\rho _j)_{j=1}^d$$ ( ρ j ) j = 1 d which characterizes the coordinate-wise sizes of the Bernstein-ellipses for u. We also prove exponential convergence in stronger norms for the approximation by DNNs with more regular, so-called “rectified power unit” activations. Finally, we extend DNN expression rate bounds also to two classes of non-holomorphic functions, in particular to d-variate, Gevrey-regular functions, and, by composition, to certain multivariate probability distribution functions with Lipschitz marginals.

Возрастающее объединение пространств Стейна с сингулярностями

We show that if $X$ is a Stein space and, if $\Omega\subset X$ is exhaustable by a sequence $\Omega_{1}\subset\Omega_{2}\subset\ldots\subset\Omega_{n}\subset\dots$ of open Stein subsets of $X$, then $\Omega$ is Stein. This generalizes a well-known result of Behnke and Stein which is obtained for $X=\mathbb{C}^{n}$ and solves the union problem, one of the most classical questions in Complex Analytic Geometry. When $X$ has dimension $2$, we prove that the same result follows if we assume only that $\Omega\subset\subset X$ is a domain of holomorphy in a Stein normal space. It is known, however, that if $X$ is an arbitrary complex space which is exhaustable by an increasing sequence of open Stein subsets $X_{1}\subset X_{2}\subset\dots\subset X_{n}\subset\dots$, it does not follow in general that $X$ is holomorphically-convex or~holomorphically-separate (even if $X$ has no singularities). One can even obtain $2$-dimensional complex manifolds on which all holomorphic functions are constant.

Analyticity and causality in conformal field theory

We investigate analyticity properties of correlation functions in conformal field theories (CFTs) in the Wightman formulation. The goal is to determine domain of holomorphy of permuted Wightman functions. We focus on crossing property of three-point functions. The domain of holomorphy of a pair of three-point functions is determined by appealing to Jost’s theorem and by adopting the technique of analytic completion. This program paves the way to address the issue of crossing for the four-point functions on a rigorous footing.

Dual Algebras and A-Measures

Weak-star closures of Gleason parts in the spectrum of a function algebra are studied. These closures relate to the bidual algebra and turn out both closed and open subsets of a compact hyperstonean space. Moreover, weak-star closures of the corresponding bands of measures are reducing. Among the applications we have a complete solution of an abstract version of the problem, whether the set of nonnegative A-measures (called also Henkin measures) is closed with respect to the absolute continuity. When applied to the classical case of analytic functions on a domain of holomorphyΩ⊂Cn, our approach avoids the use of integral formulae for analytic functions, strict pseudoconvexity, or some other regularity ofΩ. We also investigate the relation between the algebra of bounded holomorphic functions onΩand its abstract counterpart—thew* closure of a function algebraAin the dual of the band of measures generated by one of Gleason parts of the spectrum ofA.

Normed Domains of Holomorphy

We treat the classical concept of domain of holomorphy inℂnwhen the holomorphic functions considered are restricted to lie in some Banach space. Positive and negative results are presented. A new view of the casen=1is considered.

Poles ofL-functions and theta liftings for orthogonal groups

In this paper, we prove that the first occurrence of global theta liftings from any orthogonal group to either symplectic groups or metaplectic groups can be characterized completely in terms of the location of poles of certain Eisenstein series. This extends the work of Kudla and Rallis and the work of Moeglin to all orthogonal groups. As applications, we obtain results about basic structures of cuspidal automorphic representations and the domain of holomorphy of twisted standardL-functions.

Linear structure of weighted holomorphic non-extendibility

In this paper, it is proved that, for any domain G of the complex plane, there exists an infinite-dimensional closed linear submanifold M1 and a dense linear submanifold M2 with maximal algebraic dimension in the space H(G) of holomorphic functions on G such that G is the domain of holomorphy of every nonzero member f of M1 or M2 and, in addition, the growth of f near each boundary point is as fast as prescribed.