Towards an Effective Decision Procedure for LTL formulas with Constraints

This paper presents an ongoing work that is part of a more wide-ranging project whose final scope is to define a method to validate LTL formulas w.r.t. a program written in the timed concurrent constraint language tccp, which is a logic concurrent constraint language based on the concurrent constraint paradigm of Saraswat. Some inherent notions to tccp processes are non-determinism, dealing with partial information in states and the monotonic evolution of the information. In order to check an LTL property for a process, our approach is based on the abstract diagnosis technique. The concluding step of this technique needs to check the validity of an LTL formula (with constraints) in an effective way. In this paper, we present a decision method for the validity of temporal logic formulas (with constraints) built by our abstract diagnosis technique.Comment: Part of WLPE 2013 proceedings (arXiv:1308.2055

The additional difficulties for the automatic synthesis of specifications posed by logic features in functional-logic languages

This paper discusses on the additional issues for the automatic inference of algebraic property-oriented specifications which arises because of interaction between laziness and logical variables in lazy functional logic languages. We present an inference technique that overcomes these issues for the first-order fragment of the lazy functional logic language Curry. Our technique statically infers from the source code of a Curry program a specification which consists of a set of equations relating (nested) operation calls that have the same behavior. Our proposal is a (glass-box) semantics-based inference method which can guarantee, to some extent, the correctness of the inferred specification, differently from other (black-box) approaches based on testing techniques

Abstract Diagnosis for Timed Concurrent Constraint programs

The Timed Concurrent Constraint Language (tccp in short) is a concurrent logic language based on the simple but powerful concurrent constraint paradigm of Saraswat. In this paradigm, the notion of store-as-value is replaced by the notion of store-as-constraint, which introduces some differences w.r.t. other approaches to concurrency. In this paper, we provide a general framework for the debugging of tccp programs. To this end, we first present a new compact, bottom-up semantics for the language that is well suited for debugging and verification purposes in the context of reactive systems. We also provide an abstract semantics that allows us to effectively implement debugging algorithms based on abstract interpretation. Given a tccp program and a behavior specification, our debugging approach automatically detects whether the program satisfies the specification. This differs from other semiautomatic approaches to debugging and avoids the need to provide symptoms in advance. We show the efficacy of our approach by introducing two illustrative examples. We choose a specific abstract domain and show how we can detect that a program is erroneous.Comment: 16 page

Logic programs as specifications in the inductive verification of logic programs

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Bottle-brush-shaped heterostructures of NiO-ZnO nanowires: growth study and sensing properties

We present here heterostructured ZnO-NiO nanowires, constituted by a core of single crystalline ZnO nanowires, covered by poly-crystalline NiO nanorods. The bottle-brush shape was investigated by SEM and TEM, confirming that a columnar growth of NiO occurred over the ZnO core, with a preferred orientation of NiO over ZnO nanowires. The heterostructured devices are proposed for gas sensing application. Bare ZnO nanowires and heterostructured sensors with two different thicknesses of NiO poly-crystalline nanorods were analysed for acetone, ethanol, NO2 and H2 detection. All sensors maintained n-type sensing mechanism, with improved sensing performance for lower thickness of NiO, due to high catalytic activity of NiO. The sensing dynamic is also strongly modified by the presence of heterojunction of NiO/ZnO, with a reduction of response and recovery times towards ethanol and acetone at 400°C.

Tungsten Oxide Nanowires Chemical Sensors

AbstractTungsten oxide nanowires have been synthetized by a simple thermal oxidation route in an oxygen atmosphere, at low vacuum pressure. The morphology of the nanostructures was investigated by scanning electron microscope (SEM).Chemical sensors were fabricated using tungsten oxide nanowires as active layer, directly deposited on the transducer. Gas sensingperformances were evaluated towards some target chemical species (CO, NO2, NH3, Acetone, Ethanol). Firstly, a temperature screening was performed in presence of a fixed gas concentration, to determine the optimal working temperature of the sensors. Then, calibration curves for some chemical species were estimated. The influence of relative humidity was taken into account. Fabricated devices seem very promising for the detection of ammonia and carbon monoxide

A Condensed Goal-Independent Bottom-Up Fixpoint Semantics Modeling the Behavior of tccp

In this paper, we present a new compositional bottom-up semantics for the Timed Concurrent Constraint Language (tccp in short). Such semantics is defined for the full language. In particular, is able to deal with the non-monotonic characteristic of the language, which constitutes a substantial additional technical difficulty w.r.t. other compositional denotational semantics present in literature (which do not tackle the full language). The semantics is proved to be (correct and) fully abstract w.r.t. the full behavior of tccp, including infinite computations. This is particularly important since tccp has been defined to model reactive systems. The overall of these features makes our proposal particularly suitable as the basis for the definition of semantic-based program manipulation tools (like analyzers, debuggers or verifiers), especially in the context of reactive systems.Comini, M.; Titolo, L.; Villanueva García, A. (2013). A Condensed Goal-Independent Bottom-Up Fixpoint Semantics Modeling the Behavior of tccp. http://hdl.handle.net/10251/2781

Thiosemicarbazone derivatives and their metal complexes as SARS-CoV-2 main protease inhibitors

With the breakout of the pandemic caused by the SARS-CoV-2 virus in late 2019 and early 2020, the focus on drug design for the treatment of the severe respiratory syndrome caused by this virus was prompted. The main protease (MPro) of the virus has been stablished as one of the most accepted targets for the rational design of new drugs [1]. In this work, we present a series of organic compounds previously developed by our group, and their coordination complexes. Originally, these complexes had been designed as potential antiparasitic drugs, with the focus put on the main cysteine protease of the T. cruzi parasite, cruzipain. The compounds have been tested in an in vitro MPro inhibition essay and several structural redesign cycles have been performed, reaching 50% inhibition concentrations (IC50) in the low micromolar and nanomolar range. Molecular docking of the ligands and metal complexes was performed using GOLD software. The results allowed us to understand the role of co-ligands and substituents in the potential inhibition mechanism and to purpose different inhibition pathways as for example covalent metal – protein interactions and the relevant poses of the substrates in the active site of the MPro.Agencia Nacional de Investigación e Innovació

Searching for SARS-CoV-2 main protease inhibitors: coumarin thiosemicarbazone hybrids and their metal complexes

With the breakout of the pandemic caused by the SARS-CoV-2 virus in late 2019 and early 2020, the focus on drug design for the treatment of the severe respiratory syndrome caused by this virus was prompted. The main protease (MPro) of the virus has been stablished as one of the most accepted targets for the rational design of new drugs [1]. At the same time, the repositioning of drugs has gained strength in this search. In this work, we present a series of organic compounds previously used by our group, and their coordination complexes. Originally, these complexes have been prepared as potential antiparasitic drugs, with the focus put on the main cysteine protease of the T. cruzi parasite, an enzyme named cruzain. The compounds have been tested in an in vitro MPro inhibition essay and several structural redesign cycles have been performed, reaching 50% inhibition concentrations (IC50) in the low micromolar and nanomolar range. A parallel study using molecular docking in GOLD software, allowed us to understand the role of coligands and substituents in the potential inhibition mechanism and to purpose different inhibition pathways as for example covalent metal – protein interactions and the relevant poses of the substrates in the active site of the MPro.Agencia Nacional de Investigación e InnovaciónComisión Sectorial de Investigación Científic

A program analysis framework for tccp based on abstract interpretation

[EN] The timed concurrent constraint language (tccp) is a timed extension of the concurrent constraint paradigm. tccp was defined to model reactive systems, where infinite behaviors arise naturally. In previous works, a semantic framework and abstract diagnosis method for the language have been defined. On the basis of that semantic framework, this paper proposes an abstract semantics that, together with a widening operator, is suitable for the definition of different analyses for tccp programs. The abstract semantics is correct and can be represented as a finite graph where each node represents a hypothetical (abstract) computational step of the program. The widening operator allows us to guarantee the convergence of the abstract fixpoint computation.This author has been supported by the Andalusian Excellence Project P11-TIC-7659. This work has been partially supported by the EU (FEDER) and the Spanish MINECO under grants TIN 2015-69175-C4-1-R and TIN 2013-45732-C4-1-P and by Generalitat Valenciana PROMETEOII/2015/013Comini, M.; Gallardo, M.; Titolo, L.; Villanueva, A. (2017). A program analysis framework for tccp based on abstract interpretation. Formal Aspects of Computing. 29(3):531-557. https://doi.org/10.1007/s00165-016-0409-8S531557293Alpuente M, Gallardo MM, Pimentel E, Villanueva A (2006) A semantic framework for the abstract model checking of tccp programs. Theor Comput Scie 346(1): 58–95Bagnara R, Hill PM., Ricci E, Zaffanella E (2005) Precise widening operators for convex polyhedra. Sci Comput Program 58(1–2):28–56Cousot P, Cousot R (1977) Abstract interpretation: a unified lattice model for static analysis of programs by construction or approximation of fixpoints. In: Proceedings of the 4th ACM SIGACT-SIGPLAN symposium on principles of programming languages, Los Angeles, California, January 17–19. ACM Press, New York, pp 238–252Clarke EM, Grumberg O, Jha S, Lu Y, Veith H (2000) Counterexample-guided abstraction refinement. In: CAV, Lecture Notes in Computer Science, vol 1855. Springer, pp 154–169Comini M, Gallardo MM, Titolo L, Villanueva A (2015) Abstract Analysis of Universal Properties for tccp. In: Falaschi M (ed) Logic-based Program Synthesis and Transformation, 25th International Symposium, LOPSTR 2015. Revised Selected Papers, Lecture Notes in Computer Science, vol 9527. Springer, pp 163–178Comini M, Titolo L, Villanueva A (2011) Abstract diagnosis for timed concurrent constraint programs. Theory Pract Logic Programm 11(4-5):487–502Comini M, Titolo L, Villanueva A (2013) A condensed goal-independent bottom-up fixpoint modeling the behavior of tccp. Technical report, DSIC, Universitat Politècnica de València. http://riunet.upv.es/handle/10251/34328de Boer FS, Gabbrielli M, Meo MC (2000) A timed concurrent constraint language. Inf Comput 161(1): 45–83Falaschi M, Gabbrielli M, Marriott K, Palamidessi C (1993) Compositional analysis for concurrent constraint programming. In: Proceedings of the eighth annual IEEE symposium on logic in computer science, Los Alamitos, CA, USA, IEEE Computer Society Press, pp 210–221Falaschi M, Olarte C, Palamidessi C (2015) Abstract interpretation of temporal concurrent constraint programs. Theory and Pract Logic Program (TPLP) 15(3): 312–357Falaschi M, Villanueva A (2006) Automatic verification of timed concurrent constraint programs. Theory Pract Logic Program 6(3): 265–300Gallardo MM, Merino P, Pimentel E (2002) Refinement of LTL formulas for abstract model checking. In: Static analysis, 9th international symposium, SAS 2002, Madrid, Spain, September 17–20, 2002, Proceedings, pp 395–410Saraswat VA (1993) Concurrent constraint programming. The MIT Press, CambridgeSaraswat VA, Rinard M, Panangaden P (1991) The semantic foundations of concurrent constraint programming. In: Proceedings of the 18th ACM SIGPLAN-SIGACT symposium on principles of programming languages. ACM, New York, pp 333–352Zaffanella E, Giacobazzi R, Levi G (1997) Abstracting synchronization in concurrent constraint programming. J Funct Logic Program (6