Abstract: A chord of a simple polygon P is a line segment [xy]
that intersects the boundary of P only at both endpoints x and y. A
chord of P is called an interior chord provided the interior of [xy] lies
in the interior of P. P is weakly visible from [xy] if for every point v
in P there exists a point w in [xy] such that [vw] lies in P. In this
paper star-shaped, L-convex, and convex polygons are characterized
in terms of weak visibility properties from internal chords and starshaped
subsets of P. A new Krasnoselskii-type characterization of
isothetic star-shaped polygons is also presented.