Abstract
In Definition 2.2.1, we have introduced the direct power of a set—modelling the concept of a powerset—and shown that it is uniquely determined up to isomorphism. Even earlier, we have defined the natural projection of a set equipped with an equivalence to the set of its classes. We are now going to handle the direct product and direct sum.
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Notes
- 1.
These operators are conceived so as to be strict , in contrast to what the Argentinian school around Armando Haeberer has propagated some time ago in software specification; [BHSV94].
- 2.
See Sect. 3.2 of [KS00]: http://titurel.org/Papers/RATH-Titel.pdf.
- 3.
Processes may have arguments that are tuples—with the availability of its components varying over time—and in turn produce such results, in a strict or non-strict form. If tuples occur, they may just partially exist. A relational theory of partialities is already fairly developed and may be found in [Sch11a, Sch12].
References
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Schmidt, G., Winter, M. (2018). Products of Relations. In: Relational Topology. Lecture Notes in Mathematics, vol 2208. Springer, Cham. https://doi.org/10.1007/978-3-319-74451-3_3
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