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On graph products of automatic monoids

A. Veloso Da Costa — 2001

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

The graph product is an operator mixing direct and free products. It is already known that free products and direct products of automatic monoids are automatic. The main aim of this paper is to prove that graph products of automatic monoids of finite geometric type are still automatic. A similar result for prefix-automatic monoids is established.

On ranks of Jacobian varieties in prime degree extensions

Dave Mendes da Costa — 2013

Acta Arithmetica

T. Dokchitser [Acta Arith. 126 (2007)] showed that given an elliptic curve E defined over a number field K then there are infinitely many degree 3 extensions L/K for which the rank of E(L) is larger than E(K). In the present paper we show that the same is true if we replace 3 by any prime number. This result follows from a more general result establishing a similar property for the Jacobian varieties associated with curves defined by an equation of the shape f(y) = g(x) where f and g are polynomials...

Logics that are both paraconsistent and paracomplete

Newton C.A. da Costa — 1989

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

The Author describes new systems of logic (called "nonalethic") which are both paraconsistent and paracomplete. These systems are connected with the logic of vagueness and with certain philosophical problems (e.g. with some aspects of Hegel's logic).

Logics that are both paraconsistent and paracomplete

Newton C.A. da Costa — 1989

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

The Author describes new systems of logic (called "nonalethic") which are both paraconsistent and paracomplete. These systems are connected with the logic of vagueness and with certain philosophical problems (e.g. with some aspects of Hegel's logic).

On graph products of automatic monoids

A. Veloso da Costa — 2010

RAIRO - Theoretical Informatics and Applications

The graph product is an operator mixing direct and free products. It is already known that free products and direct products of automatic monoids are automatic. The main aim of this paper is to prove that graph products of automatic monoids of finite geometric type are still automatic. A similar result for prefix-automatic monoids is established.

Deux exemples sur la dimension moyenne d’un espace de courbes de Brody

Bernardo Freitas Paulo da Costa — 2013

Annales de l’institut Fourier

On étudie la dimension moyenne de l’espace de courbes 1 -Brody à valeurs dans deux surfaces complexes  : d’abord pour des surfaces de Hopf, et ensuite pour P 2 privé d’une droite. On montre dans le premier cas que la dimension moyenne est nulle via une borne sur la croissance des fonctions holomorphes faisant apparaître le lemme de la dérivée logarithmique. Pour montrer la positivité dans le deuxième exemple, on relève de la droite à son complémentaire un espace de courbes de Brody de dimension moyenne...

Using symbolic computation in the characterization of frictional instabilities involving orthotropic materials

Mohamed A. AgwaAntónio Pinto da Costa — 2015

International Journal of Applied Mathematics and Computer Science

The present work addresses the problem of determining under what conditions the impending slip state or the steady sliding of a linear elastic orthotropic layer or half space with respect to a rigid flat obstacle is dynamically unstable. In other words, we search the conditions for the occurrence of smooth exponentially growing dynamic solutions with perturbed initial conditions arbitrarily close to the steady sliding state, taking the system away from the equilibrium state or the steady sliding...

A note on paracomplete logic

Newton C. A. da CostaDiego Marconi — 1986

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

In questa nota gli Autori descrivono nuovi sistemi di logica (detta «paracompleta») connessi con la logica della vaghezza («fuzzy logic») e con le logiche paraconsistenti.

A note on paracomplete logic

Newton C. A. da CostaDiego Marconi — 1986

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti

In questa nota gli Autori descrivono nuovi sistemi di logica (detta «paracompleta») connessi con la logica della vaghezza («fuzzy logic») e con le logiche paraconsistenti.

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