Abstract:
This paper introduces CLEO, a novel preference elicitation algorithm capable of recommending complex objects in hybrid domains, characterized by both discrete and continuous attributes and constraints defined over them. The algorithm assumes minimal initial information, i.e., a set of catalog attributes, and defines decisional features as logic formulae combining Boolean and algebraic constraints over the attributes. The (unknown) utility of the decision maker (DM) is modelled as a weighted combination of features. CLEO iteratively alternates a preference elicitation step, where pairs of candidate solutions are selected based on the current utility model, and a refinement step where the utility is refined by incorporating the feedback received. The elicitation step leverages a Max-SMT solver to return optimal hybrid solutions according to the current utility model. The refinement step is implemented as learning to rank, and a sparsifying norm is used to favour the selection of few informative features in the combinatorial space of candidate decisional features. CLEO is the first preference elicitation algorithm capable of dealing with hybrid domains, thanks to the use of Max-SMT technology, while retaining uncertainty in the DM utility and noisy feedback. Experimental results on complex recommendation tasks show the ability of CLEO to quickly focus towards optimal solutions, as well as its capacity to recover from suboptimal initial choices. While no competitors exist in the hybrid setting, CLEO outperforms a state-of-the-art Bayesian preference elicitation algorithm when applied to a purely discrete task.

Abstract:
We introduce the natural lift of spacetime diffeomorphisms for conformal gravity and discuss the physical equivalence between the natural and gauge natural structure of the theory. Accordingly, we argue that conformal transformations must be introduced as gauge transformations (affecting fields but not spacetime point) and then discuss special structures implied by the splitting of the conformal group.

Abstract:
We report in this article three- and four-term recursion relations for Clebsch-Gordan coefficients of the quantum algebras $U_q(su_2)$ and $U_q(su_{1,1})$. These relations were obtained by exploiting the complementarity of three quantum algebras in a $q$-deformation of $sp(8, \gr)$.

Abstract:
Complex networks represent interactions between entities. They appear in various contexts such as sociology, biology, etc., and they generally contain highly connected subgroups called communities. Community detection is a well-studied problem and most of the algorithms aim to maximize the Newman-Girvan modularity function, the most popular being the Louvain method (it is well-suited on very large graphs). However, the classical modularity has many drawbacks: we can find partitions of high quality in graphs without community structure, e.g., on random graphs; it promotes large communities. Then, we have adapted the Louvain method to other quality functions. In this paper, we describe a generic version of the Louvain method. In particular, we give a sufficient condition to plug a quality function into it. We also show that global performance of this new version is similar to the classical Louvain algorithm, that promotes it to the best rank of the community detection algorithms.

Abstract:
Wind generated sea waves are generally regarded as an example of pure randomness in nature. Here we give a proof that the matter is not exactly so: some identical sequences of relatively large waves were found many hours apart from one another. This finding supports the theory of quasi determinism of sea waves.

Abstract:
We study a generalization of Kyle’s (1985) model to the case in which the specialist is risk-averse and does not set the transaction price according to semi-strong form efficiency. We see that Kyle’s call auction market is no longer a robust market structure, as linear Bayesian equilibria do not exist, irrespective of fundamentals, such as agents’ information, endowments and preferences. This result holds both when customers can submit only market orders and when limit orders are allowed too.

Abstract:
This paper introduces social considerations into the calculation of the price index. To this purpose, recourse is made to the concept of distributional characteristic. It is shown how an aggregate price index can be expressed as a weighted average of commodity-specific prices, with weights that depend on both the aggregate share of consumption and the way in which consumption is distributed across households. The proposed index provides a complementary basis for the analysis of the impact of inflation and for the calculation of its social value.

The cosmological constant problem is reanalyzed by imposing the limitation of the number of degrees of freedom (d.o.f.) due to entropy bounds directly in the calculation of the energy density of a field theory. It is shown that if a quantum field theory has to be consistent with gravity and holography, i.e. with an upper limit of storing information in a given area, the ultraviolet momentum cut-off is not the Planck mass, M_{p}, as naively expected, but where N_{u}is the number of d.o.f. of the universe. The energy density evaluation turns out completely consistent with Bousso’s bound on the cosmological constant value. The scale , that in the “fat graviton” theory corresponds to the graviton size, originates by a self-similar rearrangement of the elementary d.o.f. at different scales that can be seen as an infrared-ultraviolet connection.

Abstract:
Information about the Universe from Hubble’s law is consistent with that coming from the evaluation of inertial forces, supporting the picture of a steady state expansion of a black hole Universe. Backed up also by the consideration of the black body self energy, the post big bang temperature decrease is consistent with particle creation if energy conservation applies at every scale. This process is shown to provide a gravitational repulsive force which can counterbalance gravitational attraction thus allowing the possibility of a steady non-inflationary expansion. That seems to provide an alternative coherent scheme for our picture of the Universe evolution, disposing of the cosmological term, of dark energy and of the bulk of dark matter.

The scope of this paper is to examine the
complications raised by technical innovations in the financial field (fintech).
The conclusion of this enquire is that the current institutional architecture
cannot guarantee monetary and financial sustainability as long as Governments
decide to reform it using the already available instruments (cryptocurrency,
blockchain, algorithms) instead of leaving them free to operate or limiting
their use as they are doing. The same goes for any tentative to restate bank
credibility forecasting money and financial instability starting from big data
treated with traditional econometric methods.