Reduction formulas for higher order derivations and a hypergeometric identityAequationes mathematicae - Tập 95 - Trang 1053-1065 - 2021
Bruce Ebanks, André E. Kézdy
A derivation (of order 1) satisfies the reduction formula
$$f(x^k) = kx^{k-1}f(x)$$
for any integer k. In this article we find corresponding reduction formulas for derivations of higher order on commutative rings. More precisely, for every derivation f of order n and every positive integer k we fi...... hiện toàn bộ
Nonuniform exponential dichotomies and Fredholm operators for flowsAequationes mathematicae - Tập 91 - Trang 301-316 - 2017
Luis Barreira, Davor Dragičević, Claudia Valls
For the flow determined by a nonautonomous linear differential equation, we characterize the existence of a strong nonuniform exponential dichotomy in terms of the Fredholm property of a certain linear operator. We consider both cases of one-sided and two-sided exponential dichotomies. Moreover, we use the characterizations to establish the robustness of the notion of a strong nonuniform exponenti...... hiện toàn bộ