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Evolution equations in ostensible metric spaces: First-order evolutions of nonsmooth sets with nonlocal terms

Thomas Lorenz (2008)

Discussiones Mathematicae, Differential Inclusions, Control and Optimization

Similarly to quasidifferential equations of Panasyuk, the so-called mutational equations of Aubin provide a generalization of ordinary differential equations to locally compact metric spaces. Here we present their extension to a nonempty set with a possibly nonsymmetric distance. In spite of lacking any linear structures, a distribution-like approach leads to so-called right-hand forward solutions. These extensions are mainly motivated by compact subsets of the Euclidean space...

Exponential and polynomial dichotomies of operator semigroups on Banach spaces

Roland Schnaubelt (2006)

Studia Mathematica

Let A generate a C₀-semigroup T(·) on a Banach space X such that the resolvent R(iτ,A) exists and is uniformly bounded for τ ∈ ℝ. We show that there exists a closed, possibly unbounded projection P on X commuting with T(t). Moreover, T(t)x decays exponentially as t → ∞ for x in the range of P and T(t)x exists and decays exponentially as t → -∞ for x in the kernel of P. The domain of P depends on the Fourier type of X. If R(iτ,A) is only polynomially bounded, one obtains a similar result with polynomial...

Feller semigroups and degenerate elliptic operators with Wentzell boundary conditions

Kazuaki Taira, Angelo Favini, Silvia Romanelli (2001)

Studia Mathematica

This paper is devoted to the functional analytic approach to the problem of construction of Feller semigroups with Wentzell boundary conditions in the characteristic case. Our results may be stated as follows: We can construct Feller semigroups corresponding to a diffusion phenomenon including absorption, reflection, viscosity, diffusion along the boundary and jump at each point of the boundary.

Fine scales of decay of operator semigroups

Charles J. K. Batty, Ralph Chill, Yuri Tomilov (2016)

Journal of the European Mathematical Society

Motivated by potential applications to partial differential equations, we develop a theory of fine scales of decay rates for operator semigroups. The theory contains, unifies, and extends several notable results in the literature on decay of operator semigroups and yields a number of new ones. Its core is a new operator-theoretical method of deriving rates of decay combining ingredients from functional calculus and complex, real and harmonic analysis. It also leads to several results of independent...

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