A graph G is a circular-arc
graph if there is a one-to-one correspondence between the vertices of G and a
family of arcs on a circle such that two distinct vertices are adjacent when
the corresponding arcs intersect. Circular-arc graphs are characterized as
graphs whose adjacency matrix has the quasi-circular 1’s property. Two
interesting subclasses of circular-arc graphs are also discussed proper circular-arc
graphs and graphs whose augmented adjacency matrix has the circular 1’s
property.