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We extend the notion of exact completion on a category with weak finite limits to Lawvere's elementary doctrines. We show how any such doctrine admits an elementary quotient completion, which is the universal solution to adding certain quotients. We note that the elementary quotient completion can be obtained as the composite of two other universal… (More)

- Maria Emilia Maietti
- Ann. Pure Appl. Logic
- 2009

We present a two-level theory to formalize constructive mathematics as advocated in a previous paper with G. Sambin [MS05]. One level is given by an intensional type theory, called Minimal type theory. This theory extends the set-theoretic version introduced in [MS05] with collections. The other level is given by an extensional set theory that is… (More)

- MARIA EMILIA MAIETTI, DIPARTIMENTO DI MATEMATICA, PURA ED APPLICATA, Maria Emilia Maietti
- 2010

We explain in detail why the notion of list-arithmetic pretopos should be taken as the general categorical definition for the construction of arithmetic universes introduced by Andrè Joyal to give a categorical proof of Gödel's incompleteness results. We motivate this definition for three reasons: first, Joyal's arithmetic universes are list-arithmetic… (More)

We reconsider Rauszer's bi-intuitionistic logic in the framework of the logic for pragmatics: every formula is regarded as expressing an act of assertion or conjecture, where conjunction and implication are assertive and subtraction and disjunction are conjectural. The resulting system of polarized bi-intuitionistic logic (PBL) consists of two fragments,… (More)

- Maria Emilia Maietti
- TYPES
- 1998

- Maria Emilia Maietti, Silvio Valentini
- Math. Log. Q.
- 1999

In this paper we analyze an extension of Martin-Löf's intensional set theory by means of a set contructor P such that the elements of P(S) are the subsets of the set S. Since it seems natural to require some kind of extensionality on the equality among subsets, it turns out that such an extension cannot be constructive. In fact we will prove that this… (More)

- Maria Emilia Maietti
- Mathematical Structures in Computer Science
- 2005

- Maria Emilia Maietti, Paola Maneggia, Valeria de Paiva, Eike Ritter
- Applied Categorical Structures
- 2005

There are several kinds of linear typed calculus in the literature, some with their associated notion of categorical model. Our aim in this paper is to systematise the relationship between three of these linear typed calculi and their models. We point out that mere sound-ness and completeness of a linear typed calculus with respect to a class of categorical… (More)

- Maria Emilia Maietti, Silvio Valentini
- J. Symb. Log.
- 2004

- Maria Emilia Maietti, Giuseppe Rosolini
- Logica Universalis
- 2013

We apply some tools developed in categorical logic to give an abstract description of constructions used to formalize constructive mathematics in foundations based on intensional type theory. The key concept we employ is that of a Lawvere hy-perdoctrine for which we describe a notion of quotient completion. That notion includes the exact completion on a… (More)