Algebraic and graph theoretic characterizations of structured flowchart schemes

The paper concerns the relationship between graph theoretic and algebraic properties of structured flowchart schemes. For each of ten classes of flowchart schemes defined algebraically, a graph theoretic property is given which characterizes this class. The classes include the Dijkstra schemes, Elgot's CACI and G -schemes, the reducible schemes and Kosaraju's BJn-schemes. For two classes of schemes defined by a graph theoretic property, an equivalent algebraic characterization is found.