Progress in Partial Differential Equations

Preface.- Global Existence and Energy Decay of Solutions for a Nondissipative Wave Equation with a Time-Varying Delay Term.- Non-uniqueness and uniqueness in the Cauchy problem of elliptic and backward-parabolic equations.- On internal regularity of solutions to the initial value problem for the Zakharov-Kuznetsov equation.- Singular semilinear elliptic equations with subquadratic gradient terms.- On the parabolic regime of a hyperbolic equation with weak dissipation: the coercive case.- H¥ well-posedness for degenerate p-evolution models of higher order with time-dependent coefficients.- On the global solvability for semilinear wave equations with smooth time dependent propagation speeds.- Filippov Solutions to Systems of Ordinary Differential Equations with Delta Function Terms as Summands.- Resolvent estimates and scattering problems for Schr¨odinger, Klein-Gordon and wave equations.- On an Optimal Control Problem for the Wave Equation in One Space Dimension Controlled by Third Type Boundary Data.- Critical exponent for the semilinear wave equation with time or space dependent damping.- A note on a class of conservative, well-posed linear control systems.- Recent progress in smoothing estimates for evolution equations.- Differentiability of Inverse Operators.- Quasi-symmetrizer and hyperbolic equations.- Solution of the Cauchy problem for generalized Euler-Poisson-Darboux equation by the method of fractional integrals.- Global Solutions of Semilinear System of Klein-Gordon Equations in de Sitter Spacetime.