Directions sets: a generalisation of ratio sets
P Leonetti, C Sanna - Bulletin of the Australian Mathematical Society, 2020 - cambridge.org
For every integer k≥ 2 and every A⊆ N, we define the k-directions sets of A as Dk (A):={a/a:
a∈ Ak} and Dk (A):={a/a: a∈ Ak}, where· is the Euclidean norm and Ak:={a∈ Ak: ai aj for all …
a∈ Ak} and Dk (A):={a/a: a∈ Ak}, where· is the Euclidean norm and Ak:={a∈ Ak: ai aj for all …