Jose Gtz - Academia.edu (original) (raw)

Papers by Jose Gtz

Ocean & Coastal Management, 1999

The colombian government has been implementing, during the last five years, a project for the reh... more The colombian government has been implementing, during the last five years, a project for the rehabilitation of the Cie´naga Grande de Santa Marta, a coastal estuarine lagoon in the Caribbean coast of Colombia where anthropogenic activities resulted in massive mortality of the mangrove forests, water quality degradation and concomitant diminution of biodiversity, fishing resources and life quality of human populations of the area. The project was designed in two phases: the first phase set its goal in the production of an environmental management plan (EMP) for the region and was executed by three colombian institutions, CORPAMAG, INVEMAR and CORPES C.A. with the technical cooperation of the German Agency for Technical Cooperation (GTZ). The second phase of the project is implementing specific projects and activities identified and designed in the EMP. These can be summarized in four main programs: (1) management of hydrological resources; (2) management of faunal and floral resources; (3) social development and (4) institutional strengthening. Presently, the hydrological regime is being restored by dredging canals that re-communicate the estuarine system to the Magdalena River. This has already resulted in partial regeneration of the mangrove vegetation in areas immediately adjacent to the canals. Reforestation plans and plans for the management of fishing resources are being currently designed and implemented in agreement between governmental institutions and local communities.

This paper presents an experience in documentation of a spatial data set related to an environmen... more This paper presents an experience in documentation of a spatial data set related to an environmental GIS application. The aim of this work is to analyze the advantages and problems of using existing standards in creating metadata to help Brazilian institutions sharing their geospatial data sets. Several standards were identified and analyzed with respect to their completeness, ease of use, available documentation, and availability of software tools. An example of the use of FGDC metadata standard is shown and advantages and disadvantages are discussed. Results show that the FGDC standard is a good alternative for supplying Brazilian documentation demands.

The intuitionistic fragment of the call-by-name version of Curien and Herbelin's λµμ-calculus is ... more The intuitionistic fragment of the call-by-name version of Curien and Herbelin's λµμ-calculus is isolated and proved strongly normalising by means of an embedding into the simply-typed λ-calculus. Our embedding is a continuation-and-garbage-passing style translation, the inspiring idea coming from Ikeda and Nakazawa's translation of Parigot's λµ-calculus. The embedding simulates reductions while usual continuation-passing-style transformations erase permutative reduction steps. For our intuitionistic sequent calculus, we even only need "units of garbage" to be passed. We apply the same method to other calculi, namely successive extensions of the simply-typed λ-calculus leading to our intuitionistic system, and already for the simplest extension we consider (λ-calculus with generalised application), this yields the first proof of strong normalisation through a reduction-preserving embedding.

Theory of Computing Systems / Mathematical Systems Theory, 2009

In the context of intuitionistic implicational logic, we achieve a perfect correspondence (techni... more In the context of intuitionistic implicational logic, we achieve a perfect correspondence (technically an isomorphism) between sequent calculus and natural deduction, based on perfect correspondences between left-introduction and elimination, cut and substitution, and cut-elimination and normalisation. This requires an enlarged system of natural deduction that refines von Plato’s calculus. It is a calculus with modus ponens and primitive substitution; it is also a “coercion calculus”, in the sense of Cervesato and Pfenning. Both sequent calculus and natural deduction are presented as typing systems for appropriate extensions of the λ-calculus. The whole difference between the two calculi is reduced to the associativity of applicative terms (sequent calculus = right associative, natural deduction = left associative), and in fact the achieved isomorphism may be described as the mere inversion of that associativity. The novel natural deduction system is a “multiary” calculus, because “applicative terms” may exhibit a list of several arguments. But the combination of “multiarity” and left-associativity seems simply wrong, leading necessarily to non-local reduction rules (reason: normalisation, like cut-elimination, acts at the head of applicative terms, but natural deduction focuses at the tail of such terms). A solution is to extend natural deduction even further to a calculus that unifies sequent calculus and natural deduction, based on the unification of cut and substitution. In the unified calculus, a sequent term behaves like in the sequent calculus, whereas the reduction steps of a natural deduction term are interleaved with explicit steps for bringing heads to focus. A variant of the calculus has the symmetric role of improving sequent calculus in dealing with tail-active permutative conversions.

This paper gives a characterisation, via intersection types, of the strongly normalising terms of... more This paper gives a characterisation, via intersection types, of the strongly normalising terms of an intuitionistic sequent calculus (where LJ easily embeds). The soundness of the typing system is reduced to that of a well known typing system with intersection types for the ordinary λ-calculus. The completeness of the typing system is obtained from subject expansion at root position. This paper’s sequent term calculus integrates smoothly the λ-terms with generalised application or explicit substitution. Strong normalisability of these terms as sequent terms characterises their typeability in certain “natural” typing systems with intersection types. The latter are in the natural deduction format, like systems previously studied by Matthes and Lengrand et al., except that they do not contain any extra, exceptional rules for typing generalised applications or substitution.

Ocean & Coastal Management, 1999

The colombian government has been implementing, during the last five years, a project for the reh... more The colombian government has been implementing, during the last five years, a project for the rehabilitation of the Cie´naga Grande de Santa Marta, a coastal estuarine lagoon in the Caribbean coast of Colombia where anthropogenic activities resulted in massive mortality of the mangrove forests, water quality degradation and concomitant diminution of biodiversity, fishing resources and life quality of human populations of the area. The project was designed in two phases: the first phase set its goal in the production of an environmental management plan (EMP) for the region and was executed by three colombian institutions, CORPAMAG, INVEMAR and CORPES C.A. with the technical cooperation of the German Agency for Technical Cooperation (GTZ). The second phase of the project is implementing specific projects and activities identified and designed in the EMP. These can be summarized in four main programs: (1) management of hydrological resources; (2) management of faunal and floral resources; (3) social development and (4) institutional strengthening. Presently, the hydrological regime is being restored by dredging canals that re-communicate the estuarine system to the Magdalena River. This has already resulted in partial regeneration of the mangrove vegetation in areas immediately adjacent to the canals. Reforestation plans and plans for the management of fishing resources are being currently designed and implemented in agreement between governmental institutions and local communities.

This paper presents an experience in documentation of a spatial data set related to an environmen... more This paper presents an experience in documentation of a spatial data set related to an environmental GIS application. The aim of this work is to analyze the advantages and problems of using existing standards in creating metadata to help Brazilian institutions sharing their geospatial data sets. Several standards were identified and analyzed with respect to their completeness, ease of use, available documentation, and availability of software tools. An example of the use of FGDC metadata standard is shown and advantages and disadvantages are discussed. Results show that the FGDC standard is a good alternative for supplying Brazilian documentation demands.

The intuitionistic fragment of the call-by-name version of Curien and Herbelin's λµμ-calculus is ... more The intuitionistic fragment of the call-by-name version of Curien and Herbelin's λµμ-calculus is isolated and proved strongly normalising by means of an embedding into the simply-typed λ-calculus. Our embedding is a continuation-and-garbage-passing style translation, the inspiring idea coming from Ikeda and Nakazawa's translation of Parigot's λµ-calculus. The embedding simulates reductions while usual continuation-passing-style transformations erase permutative reduction steps. For our intuitionistic sequent calculus, we even only need "units of garbage" to be passed. We apply the same method to other calculi, namely successive extensions of the simply-typed λ-calculus leading to our intuitionistic system, and already for the simplest extension we consider (λ-calculus with generalised application), this yields the first proof of strong normalisation through a reduction-preserving embedding.

Theory of Computing Systems / Mathematical Systems Theory, 2009

In the context of intuitionistic implicational logic, we achieve a perfect correspondence (techni... more In the context of intuitionistic implicational logic, we achieve a perfect correspondence (technically an isomorphism) between sequent calculus and natural deduction, based on perfect correspondences between left-introduction and elimination, cut and substitution, and cut-elimination and normalisation. This requires an enlarged system of natural deduction that refines von Plato’s calculus. It is a calculus with modus ponens and primitive substitution; it is also a “coercion calculus”, in the sense of Cervesato and Pfenning. Both sequent calculus and natural deduction are presented as typing systems for appropriate extensions of the λ-calculus. The whole difference between the two calculi is reduced to the associativity of applicative terms (sequent calculus = right associative, natural deduction = left associative), and in fact the achieved isomorphism may be described as the mere inversion of that associativity. The novel natural deduction system is a “multiary” calculus, because “applicative terms” may exhibit a list of several arguments. But the combination of “multiarity” and left-associativity seems simply wrong, leading necessarily to non-local reduction rules (reason: normalisation, like cut-elimination, acts at the head of applicative terms, but natural deduction focuses at the tail of such terms). A solution is to extend natural deduction even further to a calculus that unifies sequent calculus and natural deduction, based on the unification of cut and substitution. In the unified calculus, a sequent term behaves like in the sequent calculus, whereas the reduction steps of a natural deduction term are interleaved with explicit steps for bringing heads to focus. A variant of the calculus has the symmetric role of improving sequent calculus in dealing with tail-active permutative conversions.

This paper gives a characterisation, via intersection types, of the strongly normalising terms of... more This paper gives a characterisation, via intersection types, of the strongly normalising terms of an intuitionistic sequent calculus (where LJ easily embeds). The soundness of the typing system is reduced to that of a well known typing system with intersection types for the ordinary λ-calculus. The completeness of the typing system is obtained from subject expansion at root position. This paper’s sequent term calculus integrates smoothly the λ-terms with generalised application or explicit substitution. Strong normalisability of these terms as sequent terms characterises their typeability in certain “natural” typing systems with intersection types. The latter are in the natural deduction format, like systems previously studied by Matthes and Lengrand et al., except that they do not contain any extra, exceptional rules for typing generalised applications or substitution.