arXiv subjects
Publications and source records attributed to Yu. G. Kondratiev.
Properties of a contact process in continuum for a system of two type particles one type of which is independent are considered. We study dynamics of the first and second order correlation functions, their asymptotics and dependence on parameters of the system.
We construct a new equilibrium dynamics of infinite particle systems in a Riemannian manifold $X$. This dynamics is an analog of the Kawasaki dynamics of lattice spin systems. The Kawasaki dynamics now is a process where interacting particles randomly hop over $X$. We establish conditions on the {\it a priori} explicitly given symmetrizing measure and the generator of this dynamics, under which a corresponding conservative Markov processes exists. We also outline two types of scaling limit of the equilibrium Kawasaki dynamics: one leading to an equilibrium Glauber dynamics in continuum (a birth-and-death process), and the other leading to a diffusion dynamics of interacting particles (in particular, the gradient stochastic dynamics).
The paper is devoted to the study of configuration space analysis by using the projective spectral theorem. For a manifold $X$, let $Γ_X$, resp.\ $Γ_{X,0}$ denote the space of all, resp. finite configurations in $X$. The so-called $K$-transform, introduced by A. Lenard, maps functions on $Γ_{X,0}$ into functions on $Γ_{X}$ and its adjoint $K^*$ maps probability measures on $Γ_X$ into $σ$-finite measures on $Γ_{X,0}$. For a probability measure $μ$ on $Γ_X$, $ρ_μ:=K^*μ$ is called the correlation measure of $μ$. We consider the inverse problem of existence of a probability measure $μ$ whose correlation measure $ρ_μ$ is equal to a given measure $ρ$. We introduce an operation of $\star$-convolution of two functions on $Γ_{X,0}$ and suppose that the measure $ρ$ is $\star$-positive definite, which enables us to introduce the Hilbert space ${\cal H}_ρ$ of functions on $Γ_{X,0}$ with the scalar product $(G^{(1)},G^{(2)})_{{\cal H}_ρ}= \int_{Γ_{X,0}}(G^{(1)}\star\bar G{}^{(2)})(η) ρ(dη)$. Under a condition on the growth of the measure $ρ$ on the $n$-point configuration spaces, we construct the Fourier transform in generalized joint eigenvectors of some special family $A=(A_ϕ)_{ϕ\in\D}$, $\D:=C_0^\infty(X)$, of commuting selfadjoint operators in ${\cal H}_ρ$. We show that this Fourier transform is a unitary between ${\cal H}_ρ$ and the $L^2$-space $L^2(Γ_X,dμ)$, where $μ$ is the spectral measure of $A$. Moreover, this unitary coincides with the $K$-transform, while the measure $ρ$ is the correlation measure of $μ$.
We carry out analysis and geometry on a marked configuration space $Ω^M_X$ over a Riemannian manifold $X$ with marks from a space $M$. We suppose that $M$ is a homogeneous space $M$ of a Lie group $G$. As a transformation group $\frak A$ on $Ω_X^M$ we take the ``lifting'' to $Ω_X^M$ of the action on $X\times M$ of the semidirect product of the group $\operatorname{Diff}_0(X)$ of diffeomorphisms on $X$ with compact support and the group $G^X$ of smooth currents, i.e., all $C^\infty$ mappings of $X$ into $G$ which are equal to the identity element outside of a compact set. The marked Poisson measure $π_σ$ on $Ω_X^M$ with Lévy measure $σ$ on $X\times M$ is proven to be quasiinvariant under the action of $\frak A$. Then, we derive a geometry on $Ω_X^M$ by a natural ``lifting'' of the corresponding geometry on $X\times M$. In particular, we construct a gradient $\nabla^Ω$ and a divergence $\operatorname{div}^Ω$. The associated volume elements, i.e., all probability measures $μ$ on $Ω_X^M$ with respect to which $\nabla^Ω$ and $\operatorname{div}^Ω$ become dual operators on $L^2(Ω_X^M;μ)$, are identified as the mixed marked Poisson measures with mean measure equal to a multiple of $σ$. As a direct consequence of our results, we obtain marked Poisson space representations of the group $\frak A$ and its Lie algebra $\frak a$. We investigate also Dirichlet forms and Dirichlet operators connected with (mixed) marked Poisson measures.
We carry out analysis and geometry on a marked configuration space $Ω_X^{R_+}$ over a Riemannian manifold $X$ with marks from the space $R_+$ as a natural generalization of the work {\bf [}{\it J. Func. Anal}. {\bf 154} (1998), 444--500{\bf ]}. As a transformation group $\mathfrak G$ on this space, we take the ``lifting'' to $Ω_X^{R_+}$ of the action on $X\times R_+$ of the semidirect product of the group Diff of diffeomorphisms on $X$ with compact support and the group $R_+^X$ of smooth currents, i.e., all $C^\infty$ mappings of $X$ into $R_+$ which are equal to one outside a compact set. The marked Poisson measure $π$ on $Ω_X^{R_+}$ with Lévy measure $σ$ is proven to be quasiinvariant under the action of $\mathfrak G$. Then, we derive a geometry on $Ω_X^{R_+}$ by a natural ``lifting'' of the corresponding geometry on $X\times R_+$. In particular, we construct a gradient $\nabla^Ω$ and divergence $div^Ω$. The associated volume elements, i.e., all probability measures $μ$ on $Ω_X^{R_+}$ with respect to which $\nabla^Ω$ and $div^Ω$ become dual operators on $L^2(Ω_X^{R_+} ,μ)$ are identified as the mixed Poisson measures with mean measure equal to a multiple of $σ$. As a direct consequence of our results, we obtain marked Poisson space representations of the group $\mathfrak G$ and its Lie algebra $\mathfrak g$. We investigate also Dirichlet forms and Dirichlet operators connected with (mixed) marked Poisson measures. In particular, we obtain conditions of ergodicity of the semigroups generated by the Dirichlet operators. A possible generalization of the results of the paper to the case where the marks belong to a homogeneous space of a Lie group is noted.
Gel'fand triples of test and generalized functionals in Gaussian spaces are constructed and characterized.