Trotter product formula and linear evolution equations on Hilbert spaces.

International audienceThe paper is devoted to evolution equations of the form ∂ ∂t u(t) = −(A + B(t))u(t), t ∈ I = [0, T ], on separable Hilbert spaces where A is a non-negative self-adjoint operator and B(·) is family of non-negative self-adjoint operators such that dom(A α) ⊆ dom(B(t)) for some α ∈ [0, 1) and the map A −α B(·)A −α is Hölder continuous with the Hölder exponent β ∈ (0, 1). It is shown that the solution operator U(t, s) of the evolution equation can be approximated in the operator norm by a combination of semigroups generated by A and B(t) provided the condition β > 2α − 1 is satisfied. The convergence rate for the approximation is given by the Hölder exponent β. The result is proved using the evolution semigroup approach