Let GF(q) denote the finite field with q = pn
elements and let
where each ai ∊ GF(q) and 1 < d <p. For r=2, 3, …, d we let nr denote the number of solutions (x1, …, xr) over GF(q) of
for which x1, …, xr are all different. Birch and Swinnerton-Dyer  have shown that
where each vr is a nonnegative integer depending on f and q and the constant implied by the O-symbol depends here, and throughout the paper, only on d.