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Un Cig Ji

Publications and source records attributed to Un Cig Ji.

8 recordsLinked to original sources

Stochastic Partial Differential Equations Associated with Pseudo-Differential Operators and Hilbert Space-Valued Gaussian Processes

In this paper, we prove the unique existence and investigate the $L^{p}$-regularity of solutions to stochastic partial differential equations in Hilbert spaces associated with pseudo-differential operators, driven by Hilbert space-valued Gaussian processes that satisfy certain regularity conditions for the covariance kernels of the Gaussian processes. For our purposes, we develop an $L^{p}$-regularity framework for the solutions to the stochastic partial differential equations associated with pseudo-differential operators. As the main tools, we establish the $p$-th moment maximal inequality for stochastic integrals with respect to a Hilbert space-valued Gaussian process and a Littlewood-Paley type inequality for Banach space-valued functions. Additionally, during our study, we improved the sufficient conditions for Fourier multipliers and examined the covariance kernels for Gaussian processes.

math.AP

A Generalization of Littlewood-Paley Type Inequality for Evolution Systems Associated with Pseudo Differential Operators

In this paper, we first prove that the Littlewood-Paley $g$-function, related to the convolution corresponding to the composition of pseudo-differential operator and evolution system associated with pseudo-differential operators, is a bounded operator from $L^{q}((a,b)\times \mathbb{R}^{d};V)$ with a Hilbert space $V$ into $L^{q}((a,b)\times \mathbb{R}^{d})$. Secondly, we prove that the sharp function of the Littlewood-Paley $g$-function is bounded by some maximal function. Finally, by applying Fefferman-Stein theorem and Hardy-Littlewood maximal theorem, we prove the Littlewood-Paley type inequality for evolution systems associated with pseudo-differential operators.

math.AP

Littlewood-Paley Type Inequality for Evolution Systems Associated with Pseudo-Differential Operators

In this paper, we first prove that the kernel of convolution operator, corresponding the composition of pseudo-differential operator and evolution system associated with the symbol depending on time, satisfies the Hörmander's condition. Secondly, we prove that the convolution operator is a bounded linear operator from the Besov space on $\mathbb{R}^{d}$ into $L^{q}(\mathbb{R}^{d};V)$ for a Banach space $V$. Finally, by applying the Calderón-Zygmund theorem for vector-valued functions, we prove the Littlewood-Paley type inequality for evolution systems associated with pseudo-differential operators.

math.AP

Wick calculus for noncommutative white noise corresponding to $q$-deformed commutation relations

We derive the Wick calculus for test and generalized functionals of noncommutative white noise corresponding to $q$-deformed commutation relations with $q\in(-1,1)$. We construct a Gel'fand triple centered at the $q$-deformed Fock space in which both the test, nuclear space and its dual space are algebras with respect to the addition and the Wick multiplication. Furthermore, we prove a Våge-type inequality for the Wick product on the dual space.

math.PR

Convergences of Alternating Projections in CAT($κ$) Spaces

We establish the asymptotic regularity and the $Δ$-convergence of the sequence constructed by the alternating projections to closed convex sets in a CAT($κ$) space with $κ> 0$. Furthermore, the strong convergence of the alternating von Neumann sequence is presented under certain regularity or compactness.

math.MG

KSGNS type construction for $α$-completely positive maps on Krein $C^{\ast}$-modules

In this paper, we investigate $Φ$-maps associated to a certain type of $α$-completely positive maps. We then prove a KSGNS (Kasparov--Stinespring--Gel'fand--Naimark--Segal) type theorem for $α$-completely positive maps on Krein $C^*$-modules and show that the minimal KSGNS construction is unique up to unitary equivalence. We also establish a covariant version of the KSGNS type theorem for a covariant $α$-completely positive map and study the structure of minimal covariant KSGNS constructions.

math.OA

Unitary Processes with Independent Increments

In this paper, we study unitary Gaussian processes with independent increments with which the unitary equivalence to a Hudson-Parthasarathy evolution systems is proved. This gives a generalization of results in [16] and [17] in the absence of the stationarity condition.

math.FA