The number of directions determined by a function \(f\) on a finite field
Rédei's theorem gives a restriction on the number of directions determined by all pairs of points of a \(\mathbf {GF} (q) \to \mathbf {GF} (q)\)-function. The authors essentially modify Rédei's proof slightly to exclude one more value, namely \((q + 1)/2\).
scientific article; zbMATH DE number 753625
scientific article