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New classes of analytic and Gevrey semigroups and applications

Angelo Favini, Roberto Triggiani (1993)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

We consider the operator - A + i B on a complex Hilbert space, where A is positive self-adjoint and B is self-adjoint, and where, moreover, « B is comparable to A α , α 1 », in a technical sense. Two applications are given.

New spectral criteria for almost periodic solutions of evolution equations

Toshiki Naito, Nguyen Van Minh, Jong Son Shin (2001)

Studia Mathematica

We present a general spectral decomposition technique for bounded solutions to inhomogeneous linear periodic evolution equations of the form ẋ = A(t)x + f(t) (*), with f having precompact range, which is then applied to find new spectral criteria for the existence of almost periodic solutions with specific spectral properties in the resonant case where e i s p ( f ) ¯ may intersect the spectrum of the monodromy operator P of (*) (here sp(f) denotes the Carleman spectrum of f). We show that if (*) has a bounded...

Non-autonomous stochastic Cauchy problems in Banach spaces

Mark Veraar, Jan Zimmerschied (2008)

Studia Mathematica

We study the non-autonomous stochastic Cauchy problem on a real Banach space E, d U ( t ) = A ( t ) U ( t ) d t + B ( t ) d W H ( t ) , t ∈ [0,T], U(0) = u₀. Here, W H is a cylindrical Brownian motion on a real separable Hilbert space H, ( B ( t ) ) t [ 0 , T ] are closed and densely defined operators from a constant domain (B) ⊂ H into E, ( A ( t ) ) t [ 0 , T ] denotes the generator of an evolution family on E, and u₀ ∈ E. In the first part, we study existence of weak and mild solutions by methods of van Neerven and Weis. Then we use a well-known factorisation method in the setting of evolution...

Norm continuity of c 0 -semigroups

V. Goersmeyer, L. Weis (1999)

Studia Mathematica

We show that a positive semigroup T t on L p ( Ω , ν ) with generator A and ||R(α + i β)|| → 0 as |β| → ∞ for some α ∈ ℝ is continuous in the operator norm for t>0. The proof is based on a criterion for norm continuity in terms of “smoothing properties” of certain convolution operators on general Banach spaces and an extrapolation result for the L p -scale, which may be of independent interest.

Norms for copulas.

Darsow, William F., Olsen, Elwood T. (1995)

International Journal of Mathematics and Mathematical Sciences

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