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On unitary equivalence of quasi-free Hilbert modules

Li Chen — 2009

Studia Mathematica

We characterize unitary equivalence of quasi-free Hilbert modules, which complements Douglas and Misra's earlier work [New York J. Math. 11 (2005)]. We first confine our arguments to the classical setting of reproducing Hilbert spaces and then relate our result to equivalence of Hermitian vector bundles.

Dynamic programming principle for stochastic recursive optimal control problem with delayed systems

Li ChenZhen Wu — 2012

ESAIM: Control, Optimisation and Calculus of Variations

In this paper, we study one kind of stochastic recursive optimal control problem for the systems described by stochastic differential equations with delay (SDDE). In our framework, not only the dynamics of the systems but also the recursive utility depend on the past path segment of the state process in a general form. We give the dynamic programming principle for this kind of optimal control problems and show that the value function is the viscosity solution of the corresponding infinite dimensional...

Observer-based adaptive sliding mode fault-tolerant control for the underactuated space robot with joint actuator gain faults

Ronghua LeiLi Chen — 2021

Kybernetika

An adaptive sliding mode fault-tolerant controller based on fault observer is proposed for the space robots with joint actuator gain faults. Firstly, the dynamic model of the underactuated space robot is deduced combining conservation law of linear momentum with Lagrange method. Then, the dynamic model of the manipulator joints is obtained by using the mathematical operation of the block matrices, hence the measurement of the angular acceleration of the base attitude can be omitted. Subsequently,...

Boundary blow-up solutions for a cooperative system involving the p-Laplacian

Li ChenYujuan ChenDang Luo — 2013

Annales Polonici Mathematici

We study necessary and sufficient conditions for the existence of nonnegative boundary blow-up solutions to the cooperative system Δ p u = g ( u - α v ) , Δ p v = f ( v - β u ) in a smooth bounded domain of N , where Δ p is the p-Laplacian operator defined by Δ p u = d i v ( | u | p - 2 u ) with p > 1, f and g are nondecreasing, nonnegative C¹ functions, and α and β are two positive parameters. The asymptotic behavior of solutions near the boundary is obtained and we get a uniqueness result for p = 2.

A Maschke type theorem for relative Hom-Hopf modules

Shuangjian GuoXiu-Li Chen — 2014

Czechoslovak Mathematical Journal

Let ( H , α ) be a monoidal Hom-Hopf algebra and ( A , β ) a right ( H , α ) -Hom-comodule algebra. We first introduce the notion of a relative Hom-Hopf module and prove that the functor F from the category of relative Hom-Hopf modules to the category of right ( A , β ) -Hom-modules has a right adjoint. Furthermore, we prove a Maschke type theorem for the category of relative Hom-Hopf modules. In fact, we give necessary and sufficient conditions for the functor that forgets the ( H , α ) -coaction to be separable. This leads to a generalized...

Valency seven symmetric graphs of order 2 p q

Xiao-Hui HuaLi Chen — 2018

Czechoslovak Mathematical Journal

A graph is said to be symmetric if its automorphism group acts transitively on its arcs. In this paper, all connected valency seven symmetric graphs of order 2 p q are classified, where p , q are distinct primes. It follows from the classification that there is a unique connected valency seven symmetric graph of order 4 p , and that for odd primes p and q , there is an infinite family of connected valency seven one-regular graphs of order 2 p q with solvable automorphism groups, and there are four sporadic ones...

On choosability of complete multipartite graphs K 4 , 3 * t , 2 * ( k - 2 t - 2 ) , 1 * ( t + 1 )

Guo-Ping ZhengYu-Fa ShenZuo-Li ChenJin-Feng Lv — 2010

Discussiones Mathematicae Graph Theory

A graph G is said to be chromatic-choosable if ch(G) = χ(G). Ohba has conjectured that every graph G with 2χ(G)+1 or fewer vertices is chromatic-choosable. It is clear that Ohba’s conjecture is true if and only if it is true for complete multipartite graphs. In this paper we show that Ohba’s conjecture is true for complete multipartite graphs K 4 , 3 * t , 2 * ( k - 2 t - 2 ) , 1 * ( t + 1 ) for all integers t ≥ 1 and k ≥ 2t+2, that is, c h ( K 4 , 3 * t , 2 * ( k - 2 t - 2 ) , 1 * ( t + 1 ) ) = k , which extends the results c h ( K 4 , 3 , 2 * ( k - 4 ) , 1 * 2 ) = k given by Shen et al. (Discrete Math. 308 (2008) 136-143), and c h ( K 4 , 3 * 2 , 2 * ( k - 6 ) , 1 * 3 ) = k given by He...

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