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 [Frü06] 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 [Frü98], 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.

Messa a punto di procedure per la semi-sintesi di composti ad attività antitumorale partendo da prodotti naturali. Studi di struttura-attività

Camptothecin, (CPT) is a pentacyclic alkaloid isolated for the first time from the Chinese tree Camptotheca acuminata, and which has soon attracted the attention of medicinal chemists and pharmacologists due to its promising anti-cancer activity against the most aggressive histo-types. So far, most of the synthesized camptothecin analogues are A and B ring modified compounds, which have been prepared via synthetic or semi-synthetic routes. To the best of our knowledge, a very limited number of C, D, or E ring modified analogues of CPT have been reported; moreover, the few derivatives known from the literature showed a reduced or no biological activity. This dissertation presents synthetic studies on camptothecin new derivatives along with the development of a new and general semi-synthetic methodology to obtain a large variety of analogues. We report here the semi-synthesis of a new family of 5-substituted CPT's, along with their biological activity evaluation, which will be compared with reference compounds. The use of carrier-linked prodrugs has emerged as a useful strategy to overcome some of the drawbacks related with the use of the parent drug, such as low solubility, membrane permeability properties, low oral absorption, instability, toxicity, and nontargeting. Herein we report CPT-prodrugs synthesized via ring opening of the lactone moiety as 17-O-acyl camptothecin tripartate conjugates, which bear a polyamine side chain with different architectures, as the carriers. Moreover, we found that the replacement of the oxygen atom with sulphur on the piridone D-ring, dramatically improves the potency of the novel 16a-thio-camptothecin derivatives, opening new possibilities in the modelling of this class of compounds.

A partial dependence factorial analysis to deal with selection bias in observational studis

This thesis presents a creative and practical approach to dealing with the problem of selection bias. Selection bias may be the most important vexing problem in program evaluation or in any line of research that attempts to assert causality. Some of the greatest minds in economics and statistics have scrutinized the problem of selection bias, with the resulting approaches – Rubin’s Potential Outcome Approach(Rosenbaum and Rubin,1983; Rubin, 1991,2001,2004) or Heckman’s Selection model (Heckman, 1979) – being widely accepted and used as the best fixes. These solutions to the bias that arises in particular from self selection are imperfect, and many researchers, when feasible, reserve their strongest causal inference for data from experimental rather than observational studies. The innovative aspect of this thesis is to propose a data transformation that allows measuring and testing in an automatic and multivariate way the presence of selection bias. The approach involves the construction of a multi-dimensional conditional space of the X matrix in which the bias associated with the treatment assignment has been eliminated. Specifically, we propose the use of a partial dependence analysis of the X-space as a tool for investigating the dependence relationship between a set of observable pre-treatment categorical covariates X and a treatment indicator variable T, in order to obtain a measure of bias according to their dependence structure. The measure of selection bias is then expressed in terms of inertia due to the dependence between X and T that has been eliminated. Given the measure of selection bias, we propose a multivariate test of imbalance in order to check if the detected bias is significant, by using the asymptotical distribution of inertia due to T (Estadella et al. 2005) , and by preserving the multivariate nature of data. Further, we propose the use of a clustering procedure as a tool to find groups of comparable units on which estimate local causal effects, and the use of the multivariate test of imbalance as a stopping rule in choosing the best cluster solution set. The method is non parametric, it does not call for modeling the data, based on some underlying theory or assumption about the selection process, but instead it calls for using the existing variability within the data and letting the data to speak. The idea of proposing this multivariate approach to measure selection bias and test balance comes from the consideration that in applied research all aspects of multivariate balance, not represented in the univariate variable- by-variable summaries, are ignored. The first part contains an introduction to evaluation methods as part of public and private decision process and a review of the literature of evaluation methods. The attention is focused on Rubin Potential Outcome Approach, matching methods, and briefly on Heckman’s Selection Model. The second part focuses on some resulting limitations of conventional methods, with particular attention to the problem of how testing in the correct way balancing. The third part contains the original contribution proposed , a simulation study that allows to check the performance of the method for a given dependence setting and an application to a real data set. Finally, we discuss, conclude and explain our future perspectives.

"Narrativa di frontiera". Fenomenologia di una forma aperta.

«Fiction of frontier». Phenomenology of an open form/voice. Francesco Giustini’s PhD dissertation fits into a genre of research usually neglected by the literary criticism which nevertheless is arousing much interest in recent years: the relationship between Literature and Space. In this context, the specific issue of his work consists in the category of the Frontier including its several implications for the XX century fiction. The preliminary step, at the beginning of the first section of the dissertation, is a semantic analysis: with precision, Giustini describes the meaning of the word “frontier” here declined in a multiplicity of cultural, political and geographical contexts, starting from the American frontier of the pioneers who headed for the West, to the exotic frontiers of the world, with whose the imperialistic colonization has come into contact; from the semi-uninhabited areas like deserts, highlands and virgin forests, to the ethnic frontiers between Indian and white people in South America, since the internal frontiers of the Countries like those ones between the District and the Capital City, the Centre and the Outskirts. In the next step, Giustini wants to focus on a real “ myth of the frontier”, able to nourish cultural and literary imagination. Indeed, the literature has told and chosen the frontier as the scenery for many stories; especially in the 20th Century it made the frontier a problematic space in the light of events and changes that have transformed the perception of space and our relationship with it. Therefore, the dissertation proposes a critical category, it traces the hallmarks of a specific literary phenomenon defined “ Fiction of the frontier” ,present in many literary traditions during the 20th Century. The term “Fiction” (not “Literature” or “Poetics”) does not define a genre but rather a “procedure”, focusing on a constant issue pointed out from the texts examined in this work : the strong call to the act of narration and to its oral traditions. The “Fiction of the Frontier” is perceived as an approach to the world, a way of watching and feeling the objects, an emotion that is lived and told through the story- a story where the narrator ,through his body and his voice, takes the rule of the witness. The following parts, that have an analytic style, are constructed on the basis of this theoretical and methodological reflection. The second section gives a wide range of examples into we can find the figure and the myth of the frontier through the textual analysis which range over several literary traditions. Starting from monographic chapters (Garcia Marquez, Callado, McCarthy), to the comparative reading of couples of texts (Calvino and Verga Llosa, Buzzati and Coetzee, Arguedas and Rulfo). The selection of texts is introduced so as to underline a particular aspect or a form of the frontier at every reading. This section is articulated into thematic voices which recall some actions that can be taken into the ambiguous and liminal space of the frontier (to communicate, to wait, to “trans-culturate”, to imagine, to live in, to not-live in). In this phenomenology, the frontier comes to the light as a physical and concrete element or as a cultural, imaginary, linguistic, ethnic and existential category. In the end, the third section is centered on a more defined and elaborated analysis of two authors, considered as fundamental for the comprehension of the “Fiction of the frontier”: Joseph Conrad and João Guimarães Rosa. Even if they are very different, being part of unlike literary traditions, these two authors show many connections which are pointed by the comparative analysis. Maybe Conrad is the first author that understand the feeling of the frontier , freeing himself from the adventure romance and from the exotic nineteenthcentury tradition. João Guimarães Rosa, in his turn, is the great narrator of Brazilian and South American frontier, he is the man of sertão and of endless spaces of the Centre of Brazil. His production is strongly linked to that one belonged to the author of Heart of Darkness.

Valutazione dell'efficacia delle procedure di Pushover convenzionali, modali ed adattive applicate a telai piani in c.a. regolari ed irregolari in elevazione.

The research performed during the PhD and presented in this thesis, allowed to make judgments on pushover analysis method about its application in evaluating the correct structural seismic response. In this sense, the extensive critical review of existing pushover procedures (illustrated in chapter 1) outlined their major issues related to assumptions and to hypothesis made in the application of the method. Therefore, with the purpose of evaluate the effectiveness of pushover procedures, a wide numerical investigation have been performed. In particular the attention has been focused on the structural irregularity on elevation, on the choice of the load vector and on its updating criteria. In the study eight pushover procedures have been considered, of which four are conventional type, one is multi-modal, and three are adaptive. The evaluation of their effectiveness in the identification of the correct dynamic structural response, has been done by performing several dynamic and static non-linear analysis on eight RC frames, characterized by different proprieties in terms of regularity in elevation. The comparisons of static and dynamic results have then permitted to evaluate the examined pushover procedures and to identify the expected margin of error by using each of them. Both on base shear-top displacement curves and on considered storey parameters, the best agreement with the dynamic response has been noticed on Multi-Modal Pushover procedure. Therefore the attention has been focused on Displacement-based Adative Pushover, coming to define for it an improvement strategy, and on modal combination rules, advancing an innovative method based on a quadratic combination of the modal shapes (QMC). This latter has been implemented in a conventional pushover procedure, whose results have been compared with those obtained by other multi-modal procedures. The development of research on pushover analysis is very important because the objective is to come to the definition of a simple, effective and reliable analysis method, indispensable tool in the seismic evaluation of new or existing structures.

The potential of the 3-UPU translational parallel manipulator and a procedure to select the best architecture

The 3-UPU three degrees of freedom fully parallel manipulator, where U and P are for universal and prismatic pair respectively, is a very well known manipulator that can provide the platform with three degrees of freedom of pure translation, pure rotation or mixed translation and rotation with respect to the base, according to the relative directions of the revolute pair axes (each universal pair comprises two revolute pairs with intersecting and perpendicular axes). In particular, pure translational parallel 3-UPU manipulators (3-UPU TPMs) received great attention. Many studies have been reported in the literature on singularities, workspace, and joint clearance influence on the platform accuracy of this manipulator. However, much work has still to be done to reveal all the features this topology can offer to the designer when different architecture, i.e. different geometry are considered. Therefore, this dissertation will focus on this type of the 3-UPU manipulators. The first part of the dissertation presents six new architectures of the 3-UPU TPMs which offer interesting features to the designer. In the second part, a procedure is presented which is based on some indexes, in order to allows the designer to select the best architecture of the 3-UPU TPMs for a given task. Four indexes are proposed as stiffness, clearance, singularity and size of the manipulator in order to apply the procedure.

A novel map-matching procedure for low-sampling GPS data with applications to traffic flow analysis

An extensive sample (2%) of private vehicles in Italy are equipped with a GPS device that periodically measures their position and dynamical state for insurance purposes. Having access to this type of data allows to develop theoretical and practical applications of great interest: the real-time reconstruction of traffic state in a certain region, the development of accurate models of vehicle dynamics, the study of the cognitive dynamics of drivers. In order for these applications to be possible, we first need to develop the ability to reconstruct the paths taken by vehicles on the road network from the raw GPS data. In fact, these data are affected by positioning errors and they are often very distanced from each other (~2 Km). For these reasons, the task of path identification is not straightforward. This thesis describes the approach we followed to reliably identify vehicle paths from this kind of low-sampling data. The problem of matching data with roads is solved with a bayesian approach of maximum likelihood. While the identification of the path taken between two consecutive GPS measures is performed with a specifically developed optimal routing algorithm, based on A* algorithm. The procedure was applied on an off-line urban data sample and proved to be robust and accurate. Future developments will extend the procedure to real-time execution and nation-wide coverage.

Oltre il limite invalicabile. Procedure, piani, progetti sostenibili per le aree militari dismissibili di Piacenza

The research project concerns the restoration of military real estate, starting from the procedures in progress in Italy related to dismission, with particular emphasis for Piacenza and the case study of Caserme Bixio and Nicolai (Comparto Nord/San Sisto-Cittadella). The work is aimed at defining the relationship between urban planning and rehabilitation of dismissed military areas, in order to create a synergic effort capable to face the transformation of these sites and their integration into the urban tissue. The results obtained from the various recordings performed in Italy and in USA during the preparation of this thesis may help to find a new possible scenario for the Comparto Nord and its historic buildings.

Procedure e strumenti innovativi per lo sfruttamento sostenibile delle risorse minerarie

L'approvvigionamento di risorse minerali e la tutela dell'ambiente sono spesso considerate attività contrapposte ed inconciliabili, ma in realtà rappresentano due necessità imprescindibili per le società moderne. Le georisorse, in quanto non rinnovabili, devono essere valorizzate in maniera efficiente, adoperando strumenti che garantiscano la sostenibilità ambientale, sociale ed economica degli interventi estrattivi. La necessità di tutelare il territorio e migliorare la qualità della vita delle comunità locali impone alla Pubblica Amministrazione di implementare misure per la riqualificazione di aree degradate, ma fino ai primi anni '90 la normativa di settore non prevedeva strumenti a tal proposito, e ciò ha portato alla proliferazione di siti estrattivi dismessi e abbandonati senza interventi di recupero ambientale. Il presente lavoro di ricerca fornisce contributi innovativi alla pianificazione e progettazione sostenibile delle attività estrattive, attraverso l'adozione di un approccio multidisciplinare alla trattazione del tema e l'utilizzo esperto dei Sistemi Informativi Geografici, in particolare GRASS GIS. A seguito di una approfondita analisi in merito agli strumenti e le procedure adottate nella pianificazione delle Attività Estrattive in Italia, sono stati sviluppati un metodo di indagine ed un sistema esperto per la previsione ed il controllo delle vibrazioni indotte nel terreno da volate in cava a cielo aperto, che consentono di ottimizzare la progettazione della volata e del sistema di monitoraggio delle vibrazioni grazie a specifici strumenti operativi implementati in GRASS GIS. A supporto di una più efficace programmazione di interventi di riqualificazione territoriale, è stata messa a punto una procedura per la selezione di siti dismessi e di potenziali interventi di riqualificazione, che ottimizza le attività di pianificazione individuando interventi caratterizzati da elevata sostenibilità ambientale, economica e sociale. I risultati ottenuti dimostrano la necessità di un approccio esperto alla pianificazione ed alla progettazione delle attività estrattive, incrementandone la sostenibilità attraverso l'adozione di strumenti operativi più efficienti.

Fenomeni di transizione degli organismi edilizi, criteri operativi di inserimento ambientale e procedure di intervento

La presente tesi indaga le potenzialità, in termini di criteri operativi di inserimento ambientale e procedure di intervento, che possono derivare dall’analisi dei fenomeni insediativi facendo riferimento ai concetti di ‘transizione’ e ‘resilienza’. L’attuale periodo di crisi sembra scaturire dal disequilibrio di due fattori: le esigenze umane e l’ambiente. La contestualizzazione degli interventi, il graduale adattamento alle risorse ambientali locali e la valorizzazione dei processi “dal basso” sembrano consentire di riappropriarsi sia del valore identitario dei luoghi, dando risposta ai problemi di natura sociale evidenziati, sia della eco-compatibilità delle trasformazioni, del corretto utilizzo delle risorse energetiche e della gestione delle dinamiche economiche, in risposta ai problemi ambientali analizzati. Il prefigurare applicazioni pratiche del modello di trasformazione indagato alla scala edilizia, utilizzando tavole parametriche di analisi del costruito, viste d’insieme planivolumetriche ed elaborazioni di dati e immagini, può consentire la gestione di eventuali fasi di programmazione e di pianificazione da parte delle amministrazioni finalizzate a favorire e non ostacolare i presenti e futuri fenomeni di transizione. Particolarmente significativa appare l’analisi delle diverse tendenze di ricerca progettuale in atto, con riferimento a contributi caratterizzati da un’impostazione fenomenologica e tipo-morfologica, che dimostra l’attualità degli argomenti affrontati. La ricerca di Dottorato si conclude con l’applicazione dei criteri operativi di inserimento ambientale e delle procedure di intervento individuati ad uno specifico caso di studio.