In the context of process calculus, early and late semantics correspond to two particular ways of understanding the semantics of input actions.
Suppose that we have some processes , which support an input prefix of the form
Intuitively, this prefix reads a value from channel , binds it to , and continues as .
Operationally, the semantics of this can be given in two ways.
In the early semantics version, this is given by allowing the process to emit a label for every value :
If the set of values is infinite, this means that may evolve to infinitely many processes.
In the late semantics, this is given by allowing the binding of to occur as a label instead:
Milner, Robin, Joachim Parrow, and David Walker. “A Calculus of Mobile Processes, II.” Information and Computation 100, no. 1 (1992): 41–77. https://doi.org/10.1016/0890-5401(92)90009-5.
@article{milner_1992,
title = {A calculus of mobile processes, {II}},
volume = {100},
doi = {10.1016/0890-5401(92)90009-5},
pages = {41--77},
number = {1},
journaltitle = {Information and Computation},
author = {Milner, Robin and Parrow, Joachim and Walker, David},
date = {1992}
}
Milner, Robin, Joachim Parrow, and David Walker. “Modal Logics for Mobile Processes.” Theoretical Computer Science 114, no. 1 (1993): 149–71. https://doi.org/10.1016/0304-3975(93)90156-N.
@article{milner_1993,
title = {Modal logics for mobile processes},
volume = {114},
doi = {10.1016/0304-3975(93)90156-N},
pages = {149--171},
number = {1},
journaltitle = {Theoretical Computer Science},
author = {Milner, Robin and Parrow, Joachim and Walker, David},
date = {1993},
}
Ingólfsdóttir, Anna. “Late and Early Semantics Coincide for Testing.” Theoretical Computer Science 146, no. 1–2 (July 1995): 341–49. https://doi.org/10.1016/0304-3975(94)00304-2.
@article{ingolfsdottir_1995,
title = {Late and early semantics coincide for testing},
volume = {146},
doi = {10.1016/0304-3975(94)00304-2},
pages = {341--349},
number = {1},
journaltitle = {Theoretical Computer Science},
author = {Ingólfsdóttir, Anna},
date = {1995},
}