2014/10/13 by Aleksander Ćwiszewski, Cwiszewski, Aleksander, Renata Łukasiak +1
Computer Science · Engineering · Mathematics · #Advanced Mathematical Modeling in Engineering #Analysis of PDEs (math.AP) #FOS: Mathematics #Spectral Theory in Mathematical Physics #Stability and Controllability of Differential Equations
paper · pdf · doi:10.48550/arxiv.1410.3400
openalex publication_date 2014/10/13 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We are concerned with T-periodic solutions of nonautonomous parabolic problem of the form ut = Δu + V(x) u + f(t,x,u), t >0, x ∈ ℝN, with V ∈ L^∞ (ℝN)+Lp(ℝN), p ≥ N and T-periodic continuous perturbation f:ℝN× ℝ → ℝ. The so-called resonant case is considered, i.e. when \cal N:=Ker (Δ+ V) ≠ \0\ and f is bounded by a square-integrable function. We derive a formula for the fixed point index of the associated translation along trajectories operator in terms of the Brouwer topological degree of the time average mapping f: \cal N→ \cal N being the restriction of f to \cal N. By use of the formula and continuation techniques we show that Landesman-Lazer type conditions imply the existence of T-periodic solutions.