Optimization Modulo Theories with Linear Rational Costs

In the contexts of automated reasoning (AR) and formal verification (FV), important decision problems are effectively encoded into Satisfiability Modulo Theories (SMT). In the last decade efficient SMT solvers have been developed for several theories of practical interest (e.g., linear arithmetic, arrays, bit-vectors). Surprisingly, little work has been done to extend SMT to deal with optimization problems; in particular, we are not aware of any previous work on SMT solvers able to produce solutions which minimize cost functions over arithmetical variables. This is unfortunate, since some problems of interest require this functionality. In the work described in this paper we start filling this gap. We present and discuss two general procedures for leveraging SMT to handle the minimization of linear rational cost functions, combining SMT with standard minimization techniques. We have implemented the procedures within the MathSAT SMT solver. Due to the absence of competitors in the AR, FV and SMT domains, we have experimentally evaluated our implementation against state-of-the-art tools for the domain of linear generalized disjunctive programming (LGDP), which is closest in spirit to our domain, on sets of problems which have been previously proposed as benchmarks for the latter tools. The results show that our tool is very competitive with, and often outperforms, these tools on these problems, clearly demonstrating the potential of the approach.Comment: Submitted on january 2014 to ACM Transactions on Computational Logic, currently under revision. arXiv admin note: text overlap with arXiv:1202.140

The (Non) impact of the Spanish "Tax on the Sun" on photovoltaics prosumers uptake

There is increasing scientific evidence of anthropic climate change. The need to shift to more sustainable energy systems is therefore compelling. Individuals are becoming key actors in the energy transition, as producers and sellers of the renewable energy they produce on-site. However, the practice of self-consumption requires to be underpinned by adequate policy mechanisms. Under this perspective, the Spanish Royal Decree (RD) 900/2015, also so-called "Tax on the Sun", aiming at regulating energy self-consumption and enhancing the engagement of Spanish citizens in the energy transition as prosumers, by the installation of photovoltaics, represents a challenging case study. There is anecdotal evidence that instead of supporting the diffusion of electricity self-consumption, the "Tax on the Sun" has had the opposite effect. Thus, this work aims at testing this proposition by using the synthetic control methodology (SCM), which permits to evaluate the effect of a treatment in absence of a suitable control group, as in this case. This study finds that indeed at the regional level the "Tax on the Sun" has had a negative impact, if any at all. The current barriers to prosumerism, and more broadly to the active involvement of citizens in the energy transition, are still many and policy-makers should address these shortcomings if they want to fully employ the potential that prosumerism has to offer to a just energy transition

Optimization in SMT with LA(Q) Cost Functions

In the contexts of automated reasoning and formal verification, important decision problems are effectively encoded into Satisfiability Modulo Theories (SMT). In the last decade efficient SMT solvers have been developed for several theories of practical interest (e.g., linear arithmetic, arrays, bit-vectors). Surprisingly, very few work has been done to extend SMT to deal with optimization problems; in particular, we are not aware of any work on SMT solvers able to produce solutions which minimize cost functions over arithmetical variables. This is unfortunate, since some problems of interest require this functionality. In this paper we start filling this gap. We present and discuss two general procedures for leveraging SMT to handle the minimization of LA(Q) cost functions, combining SMT with standard minimization techniques. We have implemented the proposed approach within the MathSAT SMT solver. Due to the lack of competitors in AR and SMT domains, we experimentally evaluated our implementation against state-of-the-art tools for the domain of linear generalized disjunctive programming (LGDP), which is closest in spirit to our domain, on sets of problems which have been previously proposed as benchmarks for the latter tools. The results show that our tool is very competitive with, and often outperforms, these tools on these problems, clearly demonstrating the potential of the approach.Comment: A shorter version is currently under submissio

The secret voice of the illustration: A proposal for Image Education

En una sociedad dominada por la hegemonía de la imagen, estimamos necesario tomarnos una pausa para reflexionar acerca del impacto de los mensajes visuales en la formación de la persona. En la producción de imágenes no hay inocencia alguna, el mensaje visual siempre encierra un discurso e intencionalidad determinados y se emplean unos mecanismos de manipulación mental y, sobretodo, emocional de los que a menudo no somos conscientes. Resulta en consecuencia evidente la necesidad de desarrollar en el individuo desde los primeros años la capacidad para hacer una lectura crítica del medio visual. El álbum ilustrado, frente a la urgencia del mensaje mediático, nos ofrece la posibilidad de acercar al niño a la imagen de forma mucho más sosegada, reflexiva y afectiva, dibujando un recorrido maravilloso hacia la toma de consciencia, lectura e interpretación del mensaje visual.In a society ruled by the hegemony of the images, we believe that taking a pause to reflect on the impact of the visual message on the persona’s development comes as a necessity. On the production of images there is no innocence involved. The visual message always hides particular discourses and meanings, which are used as mechanisms of mental and emotional manipulation, which are often coming as surreptitious for us. In consequence, it is evident the necessity of developing on the individual the ability to read the visual media in a more critical way. The illustrated album, versus the urge of the media’s message, offers us the possibility to educate our children on a world of images in a much more relaxed, reflexive and affective way, drawing a wonderful path towards the consciousness, reading and interpretation of the visual message

De Pippi a Prisca

En un marco actual en el que el discurso acerca de la igualdad de género ha cobrado fuerza e impulso, estimamos necesario abrir la reflexión acerca de las implicaciones que las políticas educativas vigentes han conllevado en el ámbito de la creación y promoción literaria. Reafirmando el valor de la literatura infantil y juvenil (desde ahora LIJ), como instrumento de desarrollo personal y construcción de la identidad y reconociendo que las ideologías políticas, culturales y sociales se extienden en los textos literarios para ofrecer una concreta visión del mundo, proponemos una rápida mirada acerca al panorama literario actual, en términos de producción y difusión. Frente a unas propuestas aun encorsetadas en tipificaciones sexuales u otras excesivamente moralistas y artificiosas en su afán de revertir los estereotipos de género, algunos autores escriben para los niños con sinceridad sin más propósito que narrar desde su propio sentir. En este marco destacamos la figura de Bianca Pitzorno, una de las mayores representantes de la LIJ actual en Italia, inmejorable por su capacidad por representar identidades más allá del género y por traducir literariamente los problemas del ser mujer, chica o niña en la sociedad contemporánea

La voz secreta de la ilustración: Una propuesta para la educación a la imagen

In a society ruled by the hegemony of the images, we believe that taking a pause to reflect on the impact of the visual message on the persona’s development comes as a necessity. On the production of images there is no innocence involved. The visual message always hides particular discourses and meanings, which are used as mechanisms of mental and emotional manipulation, which are often coming as surreptitious for us. In consequence, it is evident the necessity of developing on the individual the ability to read the visual media in a more critical way. The illustrated album, versus the urge of the media’s message, offers us the possibility to educate our children on a world of images in a much more relaxed, reflexive and affective way, drawing a wonderful path towards the consciousness, reading and interpretation of the visual message En una sociedad dominada por la hegemonía de la imagen, estimamos necesario tomarnos una pausa para reflexionar acerca del impacto de los mensajes visuales en la formación de la persona. En la producción de imágenes no hay inocencia alguna, el mensaje visual siempre encierra un discurso e intencionalidad determinados y se emplean unos mecanismos de manipulación mental y, sobretodo, emocional de los que a menudo no somos conscientes. Resulta en consecuencia evidente la necesidad de desarrollar en el individuo desde los primeros años la capacidad para hacer una lectura crítica del medio visual. El álbum ilustrado, frente a la urgencia del mensaje mediático, nos ofrece la posibilidad de acercar al niño a la imagen de forma mucho más sosegada, reflexiva y afectiva, dibujando un recorrido maravilloso hacia la toma de consciencia, lectura e interpretación del mensaje visual.&nbsp

De Pippi a Prisca

En un marco actual en el que el discurso acerca de la igualdad de género ha cobrado fuerza e impulso, estimamos necesario abrir la reflexión acerca de las implicaciones que las políticas educativas vigentes han conllevado en el ámbito de la creación y promoción literaria. Reafirmando el valor de la literatura infantil y juvenil (desde ahora LIJ), como instrumento de desarrollo personal y construcción de la identidad y reconociendo que las ideologías políticas, culturales y sociales se extienden en los textos literarios para ofrecer una concreta visión del mundo, proponemos una rápida mirada acerca al panorama literario actual, en términos de producción y difusión. Frente a unas propuestas aun encorsetadas en tipificaciones sexuales u otras excesivamente moralistas y artificiosas en su afán de revertir los estereotipos de género, algunos autores escriben para los niños con sinceridad sin más propósito que narrar desde su propio sentir. En este marco destacamos la figura de Bianca Pitzorno, una de las mayores representantes de la LIJ actual en Italia, inmejorable por su capacidad por representar identidades más allá del género y por traducir literariamente los problemas del ser mujer, chica o niña en la sociedad contemporánea

APPRENDENTI UCRAINI DI ITALIANO L2 IN PROGETTI DI ACCOGLIENZA: CASE-STUDY

Il presente contributo presenta uno studio di caso nell’ambito dell’insegnamento/ apprendimento dell’italiano presso un gruppo di discenti di origine ucraina rifugiati in Italia. Si presentano alcuni dati di contesto che descrivono l’immigrazione ucraina in Italia, pre e post emergenza, la situazione linguistica nel Paese di origine, le specificità dell’apprendente adulto e i contesti di accoglienza in cui si è svolta la ricerca. La ricerca, di tipo qualitativo, ha visto la somministrazione di due questionari: uno dedicato agli studenti e l’altro ai relativi docenti con quesiti sulle modalità glottodidattiche messe in atto, il loro apprezzamento e la valutazione dell’efficacia percepita. Nel contributo, dopo la descrizione delle rispettive survey, si riportano e analizzano i dati raccolti contestualizzandoli. In fase finale si provano a fornire a docenti suggerimenti e pratiche operative adatte ad immigrati adulti ucraini per un apprendimento proficuo della lingua italiana.   Ukrainian learners of Italian L2 in reception projects: case-study This contribution presents a case study in the field of teaching/learning Italian language among a group of learners who are refugees of Ukrainian origin living in Italy. Contextual data are presented which describes Ukrainian immigration to Italy, pre and post emergency, the linguistic situation in the country of origin, the specificities of the adult learner and the reception contexts in which the research was carried out. The qualitative research saw the administration of two questionnaires: one dedicated to the students and the other to the relative teachers with questions on the language teaching methods implemented, their appreciation and the evaluation of the perceived effectiveness. In the contribution, after the description of the respective surveys, the collected data are reported and analyzed by contextualizing them. In the final phase they try to provide teachers with suggestions and operational practices suitable for adult Ukrainian immigrants for a productive Italian language learning experience

Stochastic Local Search for SMT: a Preliminary Report

A popular approach to SMT is based on the integration of a DPLL SAT solver and of a decision procedure able to handle sets of atomic constraints in the underlying theory T (T-solver). In pure SAT, however, stochastic local-search (SLS) procedures sometimes outperform DPLL on satisfiable instances, in particular when dealing with unstructured problems. Therefore, it is a natural research question to wonder whether SLS can be exploited successfully also inside SMT tools. The purpose of this paper is to start investigating this issue. First, we present an algorithm integrating a Boolean SLS solver (based on the WalkSAT paradigm) with a T-solver, resulting in a basic SLS-based SMT solver. Second, we introduce a group of techniques aimed at improving the synergy between the Boolean and the T-specific component, and discuss the differences between the integration of T-solvers with a DPLL-based and a SLS-based SAT solver. Finally, we perform a preliminary experimental evaluation of our implementation (based on the integration of the UBCSAT SLS platform with the LA(Q)-solver of MathSAT) by comparing it against MathSAT, a state-of-the-art DPLL-based SMT solver, on both structured industrial problems coming from the SMT-LIB and randomly-generated unstructured problems. From this preliminary analysis we have that the performance of the SLS-based tool (i) is far from that of the DPLL-based one on SMT-LIB problems and (ii) is comparable on random problems