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2. ADJ: Goguen, J.A., Thatcher, J.W., Wagner, E., and Wright, J.B. Initial algebra semantics and continuous algebras, JACM 24(1977), pp. 68–95.
3. Barwise, J. Axioms for abstract model theory, Annals of Mathematical Logic 7(1974), pp. 221–165.
4. Bergstra, J.A., and Tucker, J.V. Top-down design and the algebra of communicating processes, Report CS-R8401, CWI, Amsterdam.
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