Skip to main content

    Valentin Keyantuo

    We study the fractional difierential equation Dfiu(t) + BDflu(t) + Au(t) = f(t); 0 • t • 2… (0 < fl < fi • 2) in periodic Lebesgue spaces.
    We use operator-valued Fourier multiplier theorems to study second order differential equations in Banach spaces. We establish maximal regularity results in Lp and Cs for strong solutions of a complete second order equation. In the second... more
    We use operator-valued Fourier multiplier theorems to study second order differential equations in Banach spaces. We establish maximal regularity results in Lp and Cs for strong solutions of a complete second order equation. In the second part, we study mild solutions for the second order problem. Two types of mild solutions are considered. When the operator A involved is the
    We obtain spectral conditions that characterize mild well-posed inhomogeneous differential equations in a general Banach space X. L p periodic solutions of first and second-order equations are considered. The results are expressed in... more
    We obtain spectral conditions that characterize mild well-posed inhomogeneous differential equations in a general Banach space X. L p periodic solutions of first and second-order equations are considered. The results are expressed in terms of operator-valued Fourier multipliers. Our approach provides a unified framework for various notions of strong and mild solutions. Applications to semilinear equations of second order in Hilbert spaces are given.
    Abstract In the first part of the paper, Gaussian estimates are used to study L^p-summability of the solution of the wave equation in L^p(Ω) associated with a general operator in divergence form with bounded coefficients. Secondly, we... more
    Abstract In the first part of the paper, Gaussian estimates are used to study L^p-summability of the solution of the wave equation in L^p(Ω) associated with a general operator in divergence form with bounded coefficients. Secondly, we prove that if Ω is a cube in \RR^ ...