Let f be a scalar field and F be a vector field. The following expressions either represent scalar fields, vector fields, or are completely meaningless. Determine which of the three applies to each expression and briefly explain why.
(a) curl f
(b) Δf
(c) divF
(d) curl(Δf)
(e) ΔF
(f) Δ(divF)
(g) div(Δf)
(h) Δ(div f)
(i) curl(curlF)
(j) div(divF)
(k) (Δf) x (divF)
(l) div(curl(Δf))