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- JIŘÍ ADÁMEK, ROBERT EL BASHIR, MANUELA SOBRAL, JIŘÍ VELEBIL, Robert El Bashir, Manuela Sobral
- 2001

We show that lax epimorphisms in the category Cat are precisely the functors P : E −→ B for which the functor P * : [B, Set] −→ [E, Set] of composition with P is fully faithful. We present two other characterizations. Firstly, lax epimorphisms are precisely the " absolutely dense " functors, i.e., functors P such that every object B of B is an absolute… (More)

- Manuela Sobral
- Applied Categorical Structures
- 1996

- George Janelidze, Manuela Sobral
- Applied Categorical Structures
- 2011

We show that the category of regular epimorphisms in a Barr exact Goursat category is almost Barr exact in the sense that (it is a regular category and) every regular epimorphism in it is an effective descent morphism.

Implications in a category can be presented as epimorphisms: an object satisfies the implication iff it is injective w.r.t. that epimorphism. G. Roçu formulated a logic for deriving an implication from other implications. We present two versions of im-plicational logics: a general one and a finitary one (for epimorphisms with finitely presentable domains… (More)

- Margarida Dias, Manuela Sobral
- Applied Categorical Structures
- 2006

A characterization of descent morphism in the category of Priestley spaces, as well as necessary and sufficient conditions for such morphisms to be effective are given. For that we embed this category in suitable categories of preordered topological spaces were descent and effective morphisms are described using the monadic description of descent. A… (More)

- C C G Moura, P B F Soares, +5 authors C J Soares
- International endodontic journal
- 2017

AIM
To investigate the ability of newly developed powdered coconut water formulas (ACP) with different osmolarities to maintain the viability of periodontal ligament (PDL) cells over time compared with other solutions.
METHODOLOGY
Dogs teeth were extracted and stored for two periods, 3 h or 24 h, in the following media: long-shelf life CW (CW),… (More)

- Nelson Martins-Ferreira, Andrea Montoli, Manuela Sobral
- Applied Categorical Structures
- 2014

The categorical definition of semidirect products was introduced by D. Bourn and G. Janelidze in [2], where they proved that, in the category of groups, this notion coincides with the classical one. A characterization of pointed categories with categorical semidirect products was given in [3]. The existence of such products imply, in particular, that the… (More)

- Manuela Sobral
- Applied Categorical Structures
- 2001

- Manuela Sobral
- Applied Categorical Structures
- 2004

We characterize the (effective) E-descent morphisms in the category Cat of small categories, when E is the class of discrete fibrations or the one of discrete cofibrations, and prove that every effective global-descent morphism is an effective E-descent morphism while its converse fails.

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