Abstract
Ann×m sonar sequence is a subset of then×m grid with exactly one point in each column, such that the\(\mathop 2\limits^m \) vectors determined by them are all distinct. We show that for fixedn the maximalm for which a sonar sequence exists satisfiesn−Cn 11/20<m<n+4n 2/3 for alln andm>n+c logn log logn for infinitely manyn.
Another problem concerns the maximal numberD of points that can be selected from then×m grid so that all the\(\mathop 2\limits^D \) vectors have slopes. We proven 1/2≪D≪n 4/5
Similar content being viewed by others
References
J. Singer: A Theorem in Finite Projective Geometry and Some Applications to Number Theory,Trans. Amer. Math. Soc.,43 (1938), 377–385.
P. Erdős, andP. Turán: On a Problem of Sidon in Additive Number Theory and Some Related Problems,J. London Math. Soc.,16 (1941), 212–215.
S. W. Golomb, andH. Taylor: Two-dimensional Synchronization Patterns for Minimum Ambiguity,IEEE Trans. Inform. Theory IT-28 (1982), 600–604.
P. Erdős, andR. K. Guy: Distinct Distances Between Lattice Points,Elemente Der Mathematik,25, (1970), 121–123.
S. W. Graham, andC. J. Ringrose: Lower Bounds for Least Quadratic Non-residues, to appear inNumber Theory at Allerton Park, Proceedings of a conference in honor of Paul T. Bateman, Allerton Park, 1989, Birkhauser Verlag, Boston.
G. H. Hardy, andE. M. Wright:An Introduction to the Theory of Numbers, 3rd Edition, 1954, Oxford.
Author information
Authors and Affiliations
Additional information
Supported by Hungarian National Foundation for Scientific Research, Grant No. 1901
Research conducted by Herbert Taylor was sponsored in part by the Office of Naval Research under ONR Contract No. N00014-90-J-1341.
Rights and permissions
About this article
Cite this article
Erdős, P., Graham, R., Ruzsa, I.Z. et al. Bounds for arrays of dots with distinct slopes or lengths. Combinatorica 12, 39–44 (1992). https://doi.org/10.1007/BF01191203
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01191203