We develop exact piecewise polynomial sequences on Alfeld splits in any spatial dimension and any polynomial degree. An Alfeld split of a simplex is obtained by connecting the vertices of an n-simplex with its barycenter. We show that, on these triangulations, the kernel of the exterior derivative has enhanced smoothness. Byproducts of this theory include characterizations of discrete divergence-free subspaces for the Stokes problem, commutative projections, and simple formulas for the dimensions of smooth polynomial spaces.Hence, κω ∈ P r+1 Λ k−1 (T ).Suppose that ω = σ a σ dλ σ ∈ P r Λ k (T ) and suppose that f = [τ (0), τ (1), τ (2), . . . , τ (s)] is an ssimplex of T . Then the trace of ω on f is given bywhere tr f a σ := a σ | f is simply the restriction of a σ to f . We say that σ ⊂ τ if {σ(1), . . . , σ(k)} ⊂ {τ (0), τ (1), . . . , τ (s)}.We define the spaceThe following result is contained in [3, Theorem 4.8].We also need a result in the case r = 0. To do this, we first state a result from Arnold et al. [3, Lemma 4.6].Proposition 2.2. Let ω ∈ P r Λ k (T ). Suppose that tr Fi ω = 0, for 1 ≤ i ≤ n and T ω ∧ η, for all η ∈ P r−n+k Λ n−k (T ).Then, ω = 0. In particular, if ω ∈ P 0 Λ k (T ) with k ≤ n − 1 satisfies tr Fi ω = 0 for 1 ≤ i ≤ n, then ω = 0.Lemma 2.3. Define the set of k-simplices that have x 0 as a vertex: