“…It is readily checked that the kernel 13) coincides with the space of divergence-free functions in D(Ω). Similarly, the kernel 14) coincides with the space of pairs (ϑ, w) in H 0 (curl, Ω) × V such that ϑ is equal to curl w in the distribution sense. We observe that, for any solution (ω, u, p) of problem (2.9), the pair (ω, u) is a solution of the following reduced problem:…”