1. Back, R.J.: Semantics of unbounded nondeterminism, in Proc. 7th ICALP, LNCS 85, pp. 51?63. Berlin, Heidelberg, New York: Springer 1980
2. Burstall, R.M.: Program proving as hand simulation with a little induction. Information Processing 74, pp. 308?312. Amsterdam: North-Holland 1974
3. Cousot, P., Cousot, R.: Induction principles for proving invariance properties of programs. In: Tools and notions for program construction. (D. Neel, ed.), pp. 75?119. Cambridge: University Press 1982
4. Cousot, P., Cousot, R.: ?A la Floyd? induction principles for proving inevitability properties of programs. In: Algebraic methods in semantics. (M. Nivat, J.C. Reynolds, eds.), pp. 277?312. Cambridge: University Press 1985
5. Research Report LRIM-83-08;P. Cousot,1983