For a finite p-group P the following three conditions are equivalent: (a) to have a (proper) partition, that is, to be the union of some proper subgroups with trivial pairwise intersections; (b) to have a proper subgroup outside of which all elements have order p; (c) to be a semidirect product P = P1o ⟨φ⟩ where P1 is a subgroup of index p and φ is a splitting automorphism of order p of P1. It ...