Transformations of Logic Programs on Infinite Lists

We consider an extension of logic programs, called \omega-programs, that can be used to define predicates over infinite lists. \omega-programs allow us to specify properties of the infinite behavior of reactive systems and, in general, properties of infinite sequences of events. The semantics of \omega-programs is an extension of the perfect model semantics. We present variants of the familiar unfold/fold rules which can be used for transforming \omega-programs. We show that these new rules are correct, that is, their application preserves the perfect model semantics. Then we outline a general methodology based on program transformation for verifying properties of \omega-programs. We demonstrate the power of our transformation-based verification methodology by proving some properties of Buechi automata and \omega-regular languages.Comment: 37 pages, including the appendix with proofs. This is an extended version of a paper published in Theory and Practice of Logic Programming, see belo

Totally correct logic program transformations via well-founded annotations

We address the problem of proving the total correctness of transformations of definite logic programs. We consider a general transformation rule, called clause replacement, which consists in transforming a program P into a new program Q by replacing a set Γ1 of clauses occurring in P by a new set Γ2 of clauses, provided that Γ1 and Γ2 are equivalent in the least Herbrand model M(P) of the program P. We propose a general method for proving that transformations based on clause replacement are totally correct, that is, M(P) = M(Q). Our method consists in showing that the transformation of P into Q can be performed by: (i) adding extra arguments to predicates, thereby deriving from the given program P an annotated program P, (ii) applying a variant of the clause replacement rule and transforming the annotated program P into a terminating annotated program Q, and (iii) erasing the annotations from Q, thereby getting Q. Our method does not require that either P or Q are terminating and it is parametric with respect to the annotations. By providing different annotations we can easily prove the total correctness of program transformations based on various versions of the popular unfolding, folding, and goal replacement rules, which can all be viewed as particular cases of our clause replacement rule

Adult lifelong learning and counselling in life transitions: Challenges for universities.

The paper aims to explore the implications of university lifelong learning on professional and personal transitions (and micro-transitions) and the role of adult counselling in supporting and facilitating them. This is a challenge for Italian Universities as national rules are being implemented in the perspective of a National Lifelong Learning System. In recent decades in Europe different research has analysed the phase betwee

Inhibition of phosphoinositide 3-kinase/protein kinase B signaling hampers the vasopressin-dependent stimulation of myogenic differentiation

Arginine-vasopressin (AVP) promotes muscle differentiation, hypertrophy, and regeneration through the combined activation of the calcineurin and Calcium/Calmodulin-dependent Protein Kinase (CaMK) pathways. The AVP system is impaired in several neuromuscular diseases, suggesting that AVP may act as a physiological factor in skeletal muscle. Since the Phosphoinositide 3-kinases/Protein Kinase B/mammalian Target Of Rapamycin (PI3K/Akt/mTOR) signaling plays a significant role in regulating muscle mass, we evaluated its role in the AVP myogenic effect. In L6 cells AKT1 expression was knocked down, and the AVP-dependent expression of mTOR and Forkhead box O3 (FoxO) was analyzed by Western blotting. The effect of the PI3K inhibitor LY294002 was evaluated by cellular and molecular techniques. Akt knockdown hampered the AVP-dependent mTOR expression while increased the levels of FoxO transcription factor. LY294002 treatment inhibited the AVP-dependent expression of Myocyte Enhancer Factor-2 (MEF2) and myogenin and prevented the nuclear translocation of MEF2. LY294002 also repressed the AVP-dependent nuclear export of histone deacetylase 4 (HDAC4) interfering with the formation of multifactorial complexes on the myogenin promoter. We demonstrate that the PI3K/Akt pathway is essential for the full myogenic effect of AVP and that, by targeting this pathway, one may highlight novel strategies to counteract muscle wasting in aging or neuromuscular disorders

Le genre Abies en Italie: écologie générale, gestion sylvicole et ressources génétiques.

International audienceLe genre Abies est représenté en Italie par deux espèces indigènes : A. alba et A. nebrodensis. A. alba (63.400 ha) est localisé dans les Alpes et dans les Apennins, jusqu'à l'Aspromonte, en Calabre. L'article fournit d'abord un aperçu historique, puis écologique de l'utilisation des sapinières. Il décrit ensuite la gestion naturelle des ressources génétiques. Importante bibliographie