Abstract
We present a new method to specify a certain class of quotient in intentional type theory, and in the calculus of inductive constructions in particular. We define the notion of “normalized types”. The main idea is to associate a normalization function to a type, instead of the usual relation. This function allows to compute on a particular element for each equivalence class, avoiding the difficult task of computing on equivalence classes themselves. We restrict ourselves to quotients that allow the construction of such a function, i.e. quotient having a canonical member for each equivalence class. This method is described as an extension of the calculus of constructions allowing normalized types. We prove that this calculus has the properties of strong normalization, subject reduction, decidability of typing. In order to show the example of the definition of ℤ by a normalized type, we finally present a pseudo Coq session.
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Courtieu, P. (2001). Normalized Types. In: Fribourg, L. (eds) Computer Science Logic. CSL 2001. Lecture Notes in Computer Science, vol 2142. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-44802-0_39
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DOI: https://doi.org/10.1007/3-540-44802-0_39
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