Constraint handling rules. Compositional semantics and program transformation

This thesis intends to investigate two aspects of Constraint Handling Rules (CHR). It proposes a compositional semantics and a technique for program transformation. CHR is a concurrent committed-choice constraint logic programming language consisting of guarded rules, which transform multi-sets of atomic formulas (constraints) into simpler ones until exhaustion [Fr��06] and it belongs to the declarative languages family. It was initially designed for writing constraint solvers but it has recently also proven to be a general purpose language, being as it is Turing equivalent [SSD05a]. Compositionality is the first CHR aspect to be considered. A trace based compositional semantics for CHR was previously defined in [DGM05]. The reference operational semantics for such a compositional model was the original operational semantics for CHR which, due to the propagation rule, admits trivial non-termination. In this thesis we extend the work of [DGM05] by introducing a more refined trace based compositional semantics which also includes the history. The use of history is a well-known technique in CHR which permits us to trace the application of propagation rules and consequently it permits trivial non-termination avoidance [Abd97, DSGdlBH04]. Naturally, the reference operational semantics, of our new compositional one, uses history to avoid trivial non-termination too. Program transformation is the second CHR aspect to be considered, with particular regard to the unfolding technique. Said technique is an appealing approach which allows us to optimize a given program and in more detail to improve run-time efficiency or spaceconsumption. Essentially it consists of a sequence of syntactic program manipulations which preserve a kind of semantic equivalence called qualified answer [Fr��98], between the original program and the transformed ones. The unfolding technique is one of the basic operations which is used by most program transformation systems. It consists in the replacement of a procedure-call by its definition. In CHR every conjunction of constraints can be considered as a procedure-call, every CHR rule can be considered as a procedure and the body of said rule represents the definition of the call. While there is a large body of literature on transformation and unfolding of sequential programs, very few papers have addressed this issue for concurrent languages. We define an unfolding rule, show its correctness and discuss some conditions in which it can be used to delete an unfolded rule while preserving the meaning of the original program. Finally, confluence and termination maintenance between the original and transformed programs are shown. This thesis is organized in the following manner. Chapter 1 gives some general notion about CHR. Section 1.1 outlines the history of programming languages with particular attention to CHR and related languages. Then, Section 1.2 introduces CHR using examples. Section 1.3 gives some preliminaries which will be used during the thesis. Subsequentely, Section 1.4 introduces the syntax and the operational and declarative semantics for the first CHR language proposed. Finally, the methodologies to solve the problem of trivial non-termination related to propagation rules are discussed in Section 1.5. Chapter 2 introduces a compositional semantics for CHR where the propagation rules are considered. In particular, Section 2.1 contains the definition of the semantics. Hence, Section 2.2 presents the compositionality results. Afterwards Section 2.3 expounds upon the correctness results. Chapter 3 presents a particular program transformation known as unfolding. This transformation needs a particular syntax called annotated which is introduced in Section 3.1 and its related modified operational semantics !0t is presented in Section 3.2. Subsequently, Section 3.3 defines the unfolding rule and prove its correctness. Then, in Section 3.4 the problems related to the replacement of a rule by its unfolded version are discussed and this in turn gives a correctness condition which holds for a specific class of rules. Section 3.5 proves that confluence and termination are preserved by the program modifications introduced. Finally, Chapter 4 concludes by discussing related works and directions for future work.

Lingue meno diffuse e corpora: studio empirico sulla terminologia amministrativa ladina

This study aims to the elaboration of juridical and administrative terminology in Ladin language, actually on the Ladin idiom spoken in Val Badia. The necessity of this study is strictly connected to the fact that in South Tyrol the Ladin language is not just safeguarded, but the editing of administrative and normative text is guaranteed by law. This means that there is a need for a unique terminology in order to support translators and editors of specialised texts. The starting point of this study are, on one side the need of a unique terminology, and on the other side the translation work done till now from the employees of the public administration in Ladin language. In order to document their efforts a corpus made up of digitalized administrative and normative documents was build. The first two chapters focuses on the state of the art of projects on terminology and corpus linguistics for lesser used languages. The information were collected thanks to the help of institutes, universities and researchers dealing with lesser used languages. The third chapter focuses on the development of administrative language in Ladin language and the fourth chapter focuses on the creation of the trilingual Italian ��� German ��� Ladin corpus made up of administrative and normative documents. The last chapter deals with the methodologies applied in order to elaborate the terminology entries in Ladin language though the use of the trilingual corpus. Starting from the terminology entry all steps are described, from term extraction, to the extraction of equivalents, contexts and definitions and of course also of the elaboration of translation proposals for not found equivalences. Finally the problems referring to the elaboration of terminology in Ladin language are illustrated.

Formazione e Competenze Professionali: una ricerca empirica sui Cassaintegrati in deroga della regione Emilia Romagna

The general theme of the present inquiry concerns the role of training and continuous updating of knowledge and skills in relation to the concept of employability and social vulnerability. The empirical research has affected the entire calendar year 2010, namely from 13 February 2010 to December 31, 2010: data refer to a very specific context or to the course funded by the Emilia Romagna region and targeted to employees in cassintegrazione notwithstanding domiciled in the region. The investigations were performed in a vocational training scheme accredited by the Emilia Romagna for the provision of publicly funded training courses. The quantitative data collected are limited to the region and distributed in all the provinces of Emilia Romagna; It addressed the issue of the role of continuing education throughout life and the importance of updating knowledge and skills, such as privileged instruments to address the instability of the labor market and what strategy to reduce the risk unemployment. Based on the different strategies that the employee puts in place during their professional careers, we introduce two concepts that are more common in the so-called knowledge society, namely the concept of social vulnerability and employability. In modern organizations becomes relevant knowledge they bring workers and the relationships that develop between people and allowing exponentially and disseminate such knowledge and skills. The knowledge thus becomes the first productive force, defined by Davenport and Prusak (1998) as "fluid combination of experience, values, contextual information and specialist knowledge that provides a framework for the evaluation and assimilation of new experience and new information ". Learning at work is a by stable explicit and conscious, and even enjoyable for everyone, especially outside of a training intervention. It then goes on to address the specific issue of training, under the current labor market increasingly deconstructed.

Il Lessico d���amore nei primi tre libri delle Odi di Orazio

Il presente studio si �� posto come obiettivo quello di redigere un lessico dei termini d���amore nella poesia di Orazio, e, specificamente, dei lemmi presenti nei primi tre libri delle Odi. L���interesse per la lirica del Venosino ci ha indotti ad affrontarne la lettura non solo considerando quelle che sono le tematiche diremo topiche della sua poetica ( modus, angulus, mors, tempus, cura, solo per citare quelle pi�� significative ), ma anche quelle meno note, quale appunto il tema dell���amore, oggetto di questo lavoro. Si �� proceduto cos�� all���analisi di ogni singolo libro di ogni ode, catalogandone ed analizzandone rispettivamente tutte le occorrenze di quei termini che abbiamo ritenuto essere propri del lessico amoroso. Il commento ad ogni libro �� stato supportato dagli studi di Nisbet-Hubbard per il primo ed il secondo libro delle Odi ( cfr. R.G.M. Nisbet-M. Hubbard, A commentary on Horace: Odes Book 1, Oxford 1970; R.G.M. Nisbet-M. Hubbard, A commentary on Horace: Odes Book 2, Oxford 1978 ) e Nisbet-Rudd per il terzo ( cfr. R.G.M. Nisbet-Rudd, A commentary on Horace: Odes Book 3, Oxford, 2003 ). Trattandosi di un lessico �� stato altres�� fondamentale il contributo dell��� Index uerborum amatorium ( Cfr. R. Pichon, De sermone amatorio apud Latinos elegiarum scriptores, Paris 1902 ) e del ThLL. Si �� infine proceduto ad individuare quei termini maggiormente significativi nell���ambito della poesia d���amore in generale, il cui riflesso �� presente anche nella poesia oraziana, con una particolare attenzione al rapporto che intercorre tra Orazio e la tradizione neoterica ed elegiaca e al lessico dei colori, che vanta numerose occorrenze nella poesia d���amore, soprattutto in riferimento alla bellezza muliebre e maschile e che quindi appare di rilevante importanza per comprendere l���estetica della poesia oraziana nel ritrarre la forma degli amanti che popolano i suoi pi�� celebri versi d���amore.

L'immagine di Roma nella cultura russa tra fine XVIII secolo e inizio XIX secolo

Nella tesi si osserva come nella cultura russa cambiava l���immagine di Roma. Se ancora alla fine del settecento l���antichit�� romana poteva risultare solamente uno strumento retorico-filologico da utilizzare per fare il proprio discorso pi�� convincente, la generazione dei decabristi la stessa antica romanit�� la accostava alla cultura e storia russe tramite gli elevati ideali civici. La romanit�� ora risultava uno strumento di analisi della esperienza storica e politica della Russia anche nel contesto europeo. Da qui nasceva una serie di modelli russi legati all���antica Roma: il Catone di Radiscev, il Bruto dei decabristi, ecc. Vi attingeva generosamente anche una corrente di lirica russo-antica con i suoi ricchi riferimenti agli autori classici, Ovidio, Tacito, Orazio. Nasceva cos�� una specie di Roma antica russa che viveva secondo le sue regole etiche ed estetiche. Con il fallimento dell���esperienza decabrista cambia anche l���approccio alle antichit��: ci si distacca dalla visione storico-morale dell���antico, Roma non �� pi�� una categoria da emulare, ma una storia a s�� stante e chiusa in s�� stessa come ogni periodo storico. Essa smette di essere un criterio universale di giudizio etico e morale. Allo stesso tempo, una parte integrante della cultura russa all���epoca era il viaggio a Roma. I russi cresciuti con interesse e amore verso la Roma antica, impazienti ed emozionati, desideravano ora di vedere quella patria dei classici. Era come se fosse un appuntamento fra gli amici di vecchia data. Si affrettava a verificare di persona le muse di storia e di poesia. E con tutto questo si imparavano ad amare tutti i defetti della Roma reale, spesso inospitale, la Roma del dolore e della fatica. La voce importante nel racconto romano dei russi era anche la Roma del cristianesimo, dove ritrovare e ricoprire la propria ���anima cristiana���.