New notion of mild solutions for nonlinear differential systems involving Riemann-Liouville derivatives of higher order with non-instantaneous impulses

Both the paper and the candidate solution prove existence and uniqueness via a Banach fixed-point argument on the weighted piecewise space PC_{2−β} using the same mild-solution operator and the same Lipschitz and resolvent hypotheses. The candidate solution is cleaner on the intervalwise definition of the contraction constant c (taking a max over j), which resolves an ambiguity in the paper’s (A5). However, the candidate solution contains a coefficient slip in the bound for the Φ_j-term from earlier free pieces (a spurious 1/λ_R factor). The paper has minor notational inconsistencies (e.g., writing ϕ_j(t, Ξ(z(t_j))) where ϕ_j(t, z(t_j)) is intended), but the overall argument and constants align and the result is correct.