On the Expressivity and Applicability of Model Representation Formalisms

A number of first-order calculi employ an explicit model representation formalism for automated reasoning and for detecting satisfiability. Many of these formalisms can represent infinite Herbrand models. The first-order fragment of monadic, shallow, linear, Horn (MSLH) clauses, is such a formalism used in the approximation refinement calculus. Our first result is a finite model property for MSLH clause sets. Therefore, MSLH clause sets cannot represent models of clause sets with inherently infinite models. Through a translation to tree automata, we further show that this limitation also applies to the linear fragments of implicit generalizations, which is the formalism used in the model-evolution calculus, to atoms with disequality constraints, the formalisms used in the non-redundant clause learning calculus (NRCL), and to atoms with membership constraints, a formalism used for example in decision procedures for algebraic data types. Although these formalisms cannot represent models of clause sets with inherently infinite models, through an additional approximation step they can. This is our second main result. For clause sets including the definition of an equivalence relation with the help of an additional, novel approximation, called reflexive relation splitting, the approximation refinement calculus can automatically show satisfiability through the MSLH clause set formalism.Comment: 15 page

Sulla risoluzione degli indirizzi IP - Parte IV - Domain Name System

Con questo articolo si conclude la pubblicazione della monografia sul riconoscimento degli indirizzi IP. Il lavoro è originato dalla attività di dottorato di Stefano Bonacina, dottorando in Bioingegneria del Politecnico di Milano. Il documento originale è stato curato e rivisto nel suo complesso dagli specialisti di reti del CILEA, anche per tenere conto delle attuali evoluzioni delle soluzioni software. Questa quarta e ultima parte, descrive un'applicazione reale dei concetti illustrati negli articoli precedenti: l'analisi degli accessi via rete ad una banca dati di immagini anatomiche. Il Visible Human Dataset, oggetto di tale analisi, è il più grande atlante di bioimmagini digitali del corpo umano, ospitato presso NLM (National Library of Medicine, Bethesda, Maryland, USA) [2], titolare dei diritti sulle immagini e presso il CILEA, uno dei quattro Mirror Site mondiali, indicato qui come MMS (Milano Mirror Site, CILEA, Milano, Italia). L'articolo descrive nel dettaglio un'analisi sugli accessi via rete all'atlante, utilizzando i concetti descritti negli articoli precedenti e alcuni pacchetti software liberamente disponibili. Le prime tre puntate sono state pubblicate sui numeri 85,86 e 87 del Bollettino del CILEA

New results on rewrite-based satisfiability procedures

Program analysis and verification require decision procedures to reason on theories of data structures. Many problems can be reduced to the satisfiability of sets of ground literals in theory T. If a sound and complete inference system for first-order logic is guaranteed to terminate on T-satisfiability problems, any theorem-proving strategy with that system and a fair search plan is a T-satisfiability procedure. We prove termination of a rewrite-based first-order engine on the theories of records, integer offsets, integer offsets modulo and lists. We give a modularity theorem stating sufficient conditions for termination on a combinations of theories, given termination on each. The above theories, as well as others, satisfy these conditions. We introduce several sets of benchmarks on these theories and their combinations, including both parametric synthetic benchmarks to test scalability, and real-world problems to test performances on huge sets of literals. We compare the rewrite-based theorem prover E with the validity checkers CVC and CVC Lite. Contrary to the folklore that a general-purpose prover cannot compete with reasoners with built-in theories, the experiments are overall favorable to the theorem prover, showing that not only the rewriting approach is elegant and conceptually simple, but has important practical implications.Comment: To appear in the ACM Transactions on Computational Logic, 49 page

Discriminability of tryptophan containing dipeptides using quantum control

We show that the coherent manipulation of molecular wavepackets in the excited states of trp-containing dipeptides allows efficient discrimination among them. Optimal dynamic discrimination fails, however, for some dipeptide couples. When considering the limited spectral resources at play (3nm bandwidth at 266nm), we discuss the concept of discriminability, which appears uncorrelated to both static spectra and relaxation lifetime

Comparative chondrogenesis of human cells in a 3D integrated experimental/computational mechanobiology model

We present an integrated experimental–computational mechanobiology model of chondrogenesis. The response of human articular chondrocytes to culture medium perfusion, versus perfusion associated with cyclic pressurisation, versus non-perfused culture, was compared in a pellet culture model, and multiphysic computation was used to quantify oxygen transport and flow dynamics in the various culture conditions. At 2 weeks of culture, the measured cell metabolic activity and the matrix content in collagen type II and aggrecan were greatest in the perfused+ pressurised pellets. The main effects of perfusion alone, relative to static controls, were to suppress collagen type I and GAG contents, which were greatest in the non-perfused pellets. All pellets showed a peripheral layer of proliferating cells, which was thickest in the perfused pellets, and most pellets showed internal gradients in cell density and matrix composition. In perfused pellets, the computed lowest oxygen concentration was 0.075mM (7.5% tension), the maximal oxygen flux was 477.5 nmol/m2/s and the maximal fluid shear stress, acting on the pellet surface, was 1.8mPa (0.018 dyn/cm2). In the non-perfused pellets, the lowest oxygen concentration was 0.003mM (0.3% tension) and the maximal oxygen flux was 102.4nmol/m2/s.Alocal correlationwas observed, between the gradients in pellet properties obtained from histology, and the oxygen fields calculated with multiphysic simulation. Our results showup-regulation of hyalinematrix protein production by human chondrocytes in response to perfusion associated with cyclic pressurisation. These results could be favourably exploited in tissue engineering applications

Efficient Encodings of First-Order Horn Formulas in Equational Logic

We present several translations from first-order Horn formulas to equational logic. The goal of these translations is to allow equational theorem provers to efficiently reason about non-equational problems. Using these translations we were able to solve 37 problems of rating 1.0 (i.e. which had not previously been automatically solved) from the TPTP

Antenatal automatic diagnosis of cleft lip via unsupervised clustering method relying on 3D facial soft tissue landmarks

Objectives Ultrasound (US) is the first-choice device to detect different types of facial dysmorphisms. Anyway, at present no standard protocol has been defined for automatic nor semi-automatic diagnosis. Even though the practitioner's contribution is core, steps towards automatism are to be undertaken. We propose a methodology for diagnosing cleft lip on 3D US scans. Methods A bounded Depth Minimum Steiner Trees (D-MST) clustering algorithm is proposed for discriminating groups of 3D US faces relying on the presence/absence of a cleft lip. The analysis of 3D facial surfaces via Differential Geometry is adopted to extract landmarks. Thus, the extracted geometrical information is elaborated to feed the unsupervised clustering algorithm and produce the classification. The clustering returns the probability of being affected by the pathology, allowing physicians to focus their attention on risky individuals for further analysis. Results The feasibility is tested upon the available 3D US scans data and then deeply investigated for a large dataset of adult individuals. 3D facial Bosphorus database is chosen for the testing, which seven cleft lip-affected individuals are added to, by artificially creating the defect. The algorithm correctly separates left and right-sided cleft lips, while healthy individuals create a unique cluster; thus, the method shows accurate diagnosis results. Conclusions Even if further testing is to be performed on tailored datasets made exclusively of fetal images, this techniques gives hefty hints for a future tailored algorithm. This method also fosters the investigation of the scientific formalisation of the "normotype", which is the representative face of a class of individuals, collecting all the principal anthropometric facial measurements, in order to recognise a normal or syndromic fetus

Persistent Müllerian Duct Syndrome in a German Shepherd Dog

In mammals, the regression of the m\ufcllerian ducts is regulated by the action of the AMH hormone which is produced by testes during embryonic development. The action of this hormone is mediated by the only known receptor AMHR2. Mutations occurring in the AHM hormone and/or in the AMHR2 receptor gene cause the lack of regression of m\ufcllerian ducts, which may therefore persist even in male embryos carrying a XY chromosomal arrangement. This is known as the persistent m\ufcllerian duct syndrome (PMDS). A female German Shepherd dog was referred to the veterinary clinic because of urinary incontinence. She also showed an anatomical structure that protruded from and enlarged the vulvar labia. From the morphological appearance, one gonad resembled an ovary and the other a testicle. The histological examination instead showed that the gonads were both testes with an underdeveloped parenchyma and without signs of spermatogenetic activity. No alterations were found with regard to the uterus which showed a correctly developed body, cervix, and horns. Genetic analysis, performed on DNA extracted from blood, showed (i) the presence of both X and Y chromosomes, (ii) the absence of chromosome XX/XY chimerism, (iii) a normal SRY gene coding sequence, (iv) a normal AMHR2 gene coding sequence, and (v) a normal AMH gene coding sequence. In this study, we report and characterize a new case of PMDS in a dog excluding that the only mutation hitherto found in the AMHR2 gene is responsible for the observed phenotype

Improving the Efficiency of Reasoning Through Structure-Based Reformulation

Abstract. We investigate the possibility of improving the efficiency of reasoning through structure-based partitioning of logical theories, combined with partitionbased logical reasoning strategies. To this end, we provide algorithms for reasoning with partitions of axioms in first-order and propositional logic. We analyze the computational benefit of our algorithms and detect those parameters of a partitioning that influence the efficiency of computation. These parameters are the number of symbols shared by a pair of partitions, the size of each partition, and the topology of the partitioning. Finally, we provide a greedy algorithm that automatically reformulates a given theory into partitions, exploiting the parameters that influence the efficiency of computation.