1. Applications of Boolean Variables to Automata Theory and Dynamic Logic;Abrahamson,1978
2. Test-Free Propositional Dynamic Logic is Weaker than PDL;Berman;Tech. Report TR 77-10-02,1977
3. Alternation;Chandra,1976
4. On the theory of programming logics;Constable,1977
5. Guarded commands, nondeterminacy and formal derivation of programs;Dijkstra;Comm. ACM 18,1975