EN
By using the well-known Leggett–Williams multiple fixed point theorem for cones, some new criteria are established for the existence of three positive periodic solutions for a class of n-dimensional functional differential equations with impulses of the form
⎧y'(t) = A(t)y(t) + g(t,yt), $t ≠ t_{j}$, j ∈ ℤ,
⎨
⎩$y(t⁺_{j}) = y(t¯_{j}) + I_{j}(y(t_{j}))$,
where $A(t) = (a_{ij}(t))_{n×n}$ is a nonsingular matrix with continuous real-valued entries.