ABSTRACT
Suppose c is any set of points in a PG(2, n). A line l is called an i-secant of c if l and c have i common points. In particular a 2-secant is simply called a secant, a 1-secant is a tangent , and a 0-secant is an external line to c. A set c that has no i-secant for i > k is called a k-arc.
