ﻻ يوجد ملخص باللغة العربية
Motivated by applications to stochastic differential equations, an extension of H{o}rmanders hypoellipticity theorem is proved for second-order degenerate elliptic operators with non-smooth coefficients. The main results are established using point-wise Bessel kernel estimates and a weighted Sobolev inequality of Stein and Weiss. Of particular interest is that our results apply to operators with quite general first-order terms.
We consider Keldysh-type operators, $ P = x_1 D_{x_1}^2 + a (x) D_{x_1} + Q (x, D_{x} ) $, $ x = ( x_1, x) $ with analytic coefficients, and with $ Q ( x, D_{x} ) $ second order, principally real and elliptic in $ D_{x} $ for $ x $ near zero. We show
This paper is concerned with solution in H{o}lder spaces of the Cauchy problem for linear and semi-linear backward stochastic partial differential equations (BSPDEs) of super-parabolic type. The pair of unknown variables are viewed as deterministic s
The commutative ambiguity of a context-free grammar G assigns to each Parikh vector v the number of distinct leftmost derivations yielding a word with Parikh vector v. Based on the results on the generalization of Newtons method to omega-continuous s
A classical theorem of Herglotz states that a function $nmapsto r(n)$ from $mathbb Z$ into $mathbb C^{stimes s}$ is positive definite if and only there exists a $mathbb C^{stimes s}$-valued positive measure $dmu$ on $[0,2pi]$ such that $r(n)=int_0^{2
We analyse conformal gauge, or isotropic, singularities in cosmological models in general relativity. Using the calculus of tractors, we find conditions in terms of tractor curvature for a local extension of the conformal structure through a cosmolog