EN
A new approach to differentiation on a time scale 𝕋 is presented. We give a suitable generalization of the Vitali Lemma and apply it to prove that every increasing function f: 𝕋 → ℝ has a right derivative f₊'(x) for $μ_{Δ}$-almost all x ∈ 𝕋. Moreover, $∫_{[a,b)} f₊'(x)dμ_{Δ} ≤ f(b) - f(a)$.