1,989 research outputs found

    On P-transitive graphs and applications

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    We introduce a new class of graphs which we call P-transitive graphs, lying between transitive and 3-transitive graphs. First we show that the analogue of de Jongh-Sambin Theorem is false for wellfounded P-transitive graphs; then we show that the mu-calculus fixpoint hierarchy is infinite for P-transitive graphs. Both results contrast with the case of transitive graphs. We give also an undecidability result for an enriched mu-calculus on P-transitive graphs. Finally, we consider a polynomial time reduction from the model checking problem on arbitrary graphs to the model checking problem on P-transitive graphs. All these results carry over to 3-transitive graphs.Comment: In Proceedings GandALF 2011, arXiv:1106.081

    Bisimulation quantifiers and uniform interpolation for guarded first order logic

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    The idea that the good model-theoretic and algorithmic properties of Modal Logics are due to the guarded nature of their quantification was put forward by Andreka, van Benthem and Nemeti in a series of papers in the 1990s, exploiting the satisfiability problem, the tree model property, and other similar properties of the Guarded Fragment of First Order Logic(GF). Since then, further work on the Guarded Fragment has been done by various authors, in some cases reinforcing this idea, in some others not. At least at first sight, Craig interpolation is on the negative side: there are implications in GF without an interpolant in GF, while Modal Logic (and even the \u3bc-calculus, a powerful extension of Modal Logic) enjoys a much stronger form of interpolation, the uniform one, in which the interpolant of a valid implication not only exists, but only depends on the antecedent and on the common language of antecedent and consequent. However, Hoogland and Marx proved that Craig interpolation is restored in GFif we consider the modal character of GFwith more attention, that is, if relations appearing on guards are viewed as \u201cmodalities\u201d and the rest as \u201cpropositions\u201d, and only the latter enter in the common language. In this paper we strengthen this result by showing that GF enjoys a Modal Uniform Interpolation Theorem (in the sense of Hoogland and Marx)

    Bisimulation Quantifiers and Uniform Interpolation for Guarded First Order Logic

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    The idea that the good model-theoretic and algorithmic properties of Modal Logics are due to the guarded nature of their quantification was put forward by Andreka, van Benthem and Nemeti in a series of papers in the 1990s, exploiting the satisfiability problem, the tree model property, and other similar properties of the Guarded Fragment of First Order Logic (GF). Since then, further work on the Guarded Fragment has been done by various authors, in some cases reinforcing this idea, in some others not. At least at first sight, Craig interpolation is on the negative side: there are implications in GF without an interpolant in GF, while Modal Logic (and even the μ-calculus, a powerful extension of Modal Logic) enjoys a much stronger form of interpolation, the uniform one, in which the interpolant of a valid implication not only exists, but only depends on the antecedent and on the common language of antecedent and consequent. However, Hoogland and Marx proved that Craig interpolation is restored in GF if we consider the modal character of GF with more attention, that is, if relations appearing on guards are viewed as “modalities” and the rest as “propositions”, and only the latter enter in the common language. In this paper we strengthen this result by showing that GF enjoys a Modal Uniform Interpolation Theorem (in the sense of Hoogland and Marx)

    On Modal {\mu}-Calculus over Finite Graphs with Bounded Strongly Connected Components

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    For every positive integer k we consider the class SCCk of all finite graphs whose strongly connected components have size at most k. We show that for every k, the Modal mu-Calculus fixpoint hierarchy on SCCk collapses to the level Delta2, but not to Comp(Sigma1,Pi1) (compositions of formulas of level Sigma1 and Pi1). This contrasts with the class of all graphs, where Delta2=Comp(Sigma1,Pi1)

    ‎On The Spectrum of Countable MV-algebras

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    ‎In this paper we consider MV-algebras and their prime spectrum‎. ‎We show that there is an uncountable MV-algebra that has the same spectrum as the free MV-algebra over one element‎, ‎that is‎, ‎the MV-algebra Free1Free_1 of McNaughton functions from [0,1][0,1] to [0,1][0,1]‎, ‎the continuous‎, ‎piecewise linear functions with integer coefficients‎. ‎The construction is heavily based on Mundici equivalence between MV-algebras and lattice ordered abelian groups with the strong unit‎. ‎Also‎, ‎we heavily use the fact that two MV-algebras have the same spectrum if and only if their lattice of principal ideals is isomorphic‎.‎As an intermediate step we consider the MV-algebra A1A_1 of continuous‎, ‎piecewise linear functions with rational coefficients‎. ‎It is known that A1A_1 contains Free1Free_1‎, ‎and that A1A_1 and Free1Free_1 are equispectral‎. ‎However‎, ‎A1A_1 is in some sense easy to work with than Free1Free_1‎. Now‎, ‎A1A_1 is still countable‎. ‎To build an equispectral uncountable MV-algebra A2A_2‎, ‎we consider certain ``almost rational'' functions on [0,1][0,1]‎, ‎which are rational in every initial segment of [0,1][0,1]‎, ‎but which can have an irrational limit in 11‎.‎We exploit heavily‎, ‎via Mundici equivalence‎, ‎the properties of divisible lattice ordered abelian groups‎, ‎which have an additional structure of vector spaces over the rational field‎

    A pro longevity role for cellular senescence

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    Cellular senescence is a fundamental process that may play positive or detrimental roles for the organism. It is involved in tissue development and in tumor prevention although during aging is becoming a detrimental process contributing to the decline of tissue functions. In previous investigations, we have uncovered a better capacity to detect DNA damage in cells from long-lived mammals. Here, we report that cultured cells derived from long-lived species have a higher propensity to undergo senescence when challenged with DNA damage than cells derived from short-lived species. Using a panel of cells derived from six mammals, which range in lifespan from 3-4 years up to 120 years, we examined cell cycle response, induction of apoptosis and of cellular senescence. All species exhibited a cell cycle arrest while induction of apoptosis was variable. However, a significant positive correlation was found between the relative percent of cells, within a population which entered senescence following damage, and the lifespan of the species. We suggest that cellular senescence may have a positive role during development allowing it to contribute to the evolution of longevity

    Lifestyles and sexuality in men and women: the gender perspective in sexual medicine

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    Sexual health is strictly related with general health in both genders. In presence of a sexual dysfunction, the expert in sexual medicine aims to discover the specific weight of the physical and psychological factors can cause or con-cause the sexual problem. At the same time, a sexual dysfunction can represent a marker of the future development of a Non-communicable diseases (NCDss) as cardiovascular or metabolic diseases.In the evaluation phase, the sexual health specialist must focus on these aspects, focusing especially on the risk and protective factors that could impact on both male and female sexuality.This article presents a review of researches concerning healthy and unhealthy lifestyles and their contribute in the development of sexual quality of life in a gender-dependent manner.Among the unhealthy lifestyle, obesity contributes mostly to the development of sexual dysfunctions, due to its negative impact on cardiovascular and metabolic function. Tobacco smoking, alcohol - substance abuse and chronic stress lead to the development of sexual dysfunction in a med-long term.In order to guarantee a satisfying sexual quality of life, sexual health specialists have the responsibility to guide the patient through the adoption of healthy lifestyles, such as avoiding drugs, smoke and excessive alcohol, practicing a regular physical activity, following a balanced diet and use stress-management strategies, even before proposing both pharmaco- and/or psychotherapies

    Trends in adolescent overweight prevalence in Italy according to socioeconomic position

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    BACKGROUND: The aim of this research is to update the trend in overweight (including obesity) prevalence among Italian adolescents, evaluating possible differences by age and gender, and analyzing their relationships with socioeconomic status, between 2002 and 2014. METHODS: The present study is based on data from the Italian HBSC study at four time points (2002, 2006, 2010 and 2014), which involved 15 035 adolescents, aged 11-13-15 (7540 boys and 7495 girls). RESULTS: Gender and age were associated with the occurrence of overweight. In all surveys, boys had a higher prevalence of excess weight compared to girls (p < 0.001), but only among girls there was a significant increasing trend (from 11.2% in 2002 to 13.3% in 2014). From 2002 to 2014, the risk of being overweight was inversely associated with the economic level of the family, for both genders and all age groups. CONCLUSIONS: Data collected between 2002 and 2014 in Italy showed a low overall increase in prevalence of obesity and overweight and an inverse association between SES and obesity in all age groups and in both genders. These findings suggest that concerted, multi-sectorial, efforts are needed in Italy, in combination with a sound political will, focused on reducing social inequality associate

    Self-reported recurrent pain and medicine use among 15- year-olds: Results from the HBSC Italian study

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    Background: The prevalence of adolescent pain varies considerably across epidemiological studies, and little information is available on pain-related behaviours among adolescents, including medicine use. The aims of this study were: (1) to examine the prevalence of recurrent pain among 15-year-old adolescents in Italy; (2) to investigate the association between recurrent pain and medicine use among boys and girls; and (3) to evaluate the consistency of these associations across regions. Methods: The World Health Organization (WHO) collaborative International Health Behaviour in School-aged Children 2013/2014 study collected self-reported data on pain and medicine use from 13611 15-year-old adolescents in 21 Italian regions. We used multi-level multivariate logistic regression, stratified by gender, to analyse the association between recurrent pain and medicine use for headache, stomachache, nervousness and difficulties in getting to sleep. Results: On average, across all regions, almost 45% of adolescents reported recurrent headache, more than 30% reported recurrent backache and approximately 30% reported recurrent stomachache. Although the prevalence of both pain and medicine use was much higher among girls, the association between pain and medicine use was similarly strong in adolescents of both genders. Adolescents with recurrent pain proved more likely to use medicines also for non-corresponding pain, nervousness and difficulties in getting to sleep. The association between recurrent pain and medicine use was consistent across regions despite large inter-regional differences in the prevalence of both phenomena. Conclusions: Recurrent pain in adolescence is common nationwide. Adolescents with recurrent pain are more likely to use medicines in general. Recurrent pain and medicine use should be addressed by adolescent health policies
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