@article{eprints366,
           pages = {391--423},
           title = {A Process Algebraic View of Input/Output Automata},
          volume = {138},
            year = {1995},
          author = {Rocco De Nicola and Roberto Segala},
       publisher = {Elsevier},
         journal = {Theoretical Computer Science},
          number = {2},
             url = {http://eprints.imtlucca.it/366/},
        abstract = {Input/output automata are a widely used formalism for the specification and verification of concurrent algorithms. Unfortunately, they lack an algebraic characterization, a formalization which has been fundamental for the success of theories like CSP, CCS and ACP. We present a many-sorted algebra for I/O automata that takes into account notions such as interface, input enabling, and local control. It is sufficiently expressive for representing all finitely branching transition systems; hence, all I/O automata with a finitely branching transition relation. Our presentation includes a complete axiomatization of the external trace preorder relation over recursion-free processes with input and output.}
}