Diagnosis and Prediction of Market Rebounds in Financial Markets

We introduce the concept of "negative bubbles" as the mirror image of standard financial bubbles, in which positive feedback mechanisms may lead to transient accelerating price falls. To model these negative bubbles, we adapt the Johansen-Ledoit-Sornette (JLS) model of rational expectation bubbles with a hazard rate describing the collective buying pressure of noise traders. The price fall occurring during a transient negative bubble can be interpreted as an effective random downpayment that rational agents accept to pay in the hope of profiting from the expected occurrence of a possible rally. We validate the model by showing that it has significant predictive power in identifying the times of major market rebounds. This result is obtained by using a general pattern recognition method which combines the information obtained at multiple times from a dynamical calibration of the JLS model. Error diagrams, Bayesian inference and trading strategies suggest that one can extract genuine information and obtain real skill from the calibration of negative bubbles with the JLS model. We conclude that negative bubbles are in general predictably associated with large rebounds or rallies, which are the mirror images of the crashes terminating standard bubbles.Comment: 49 pages, 14 figure

Recovering Grammar Relationships for the Java Language Specification

Grammar convergence is a method that helps discovering relationships between different grammars of the same language or different language versions. The key element of the method is the operational, transformation-based representation of those relationships. Given input grammars for convergence, they are transformed until they are structurally equal. The transformations are composed from primitive operators; properties of these operators and the composed chains provide quantitative and qualitative insight into the relationships between the grammars at hand. We describe a refined method for grammar convergence, and we use it in a major study, where we recover the relationships between all the grammars that occur in the different versions of the Java Language Specification (JLS). The relationships are represented as grammar transformation chains that capture all accidental or intended differences between the JLS grammars. This method is mechanized and driven by nominal and structural differences between pairs of grammars that are subject to asymmetric, binary convergence steps. We present the underlying operator suite for grammar transformation in detail, and we illustrate the suite with many examples of transformations on the JLS grammars. We also describe the extraction effort, which was needed to make the JLS grammars amenable to automated processing. We include substantial metadata about the convergence process for the JLS so that the effort becomes reproducible and transparent

Description of double beta decay within continuum-QRPA

A method to calculate the nuclear double beta decay ($2\nu\beta\beta$- and $0\nu\beta\beta$-) amplitudes within the continuum random phase approximation (cQRPA) is formulated. Calculations of the $\beta\beta$ transition amplitudes within the cQRPA are performed for ^{76}Ge, ^{100}Mo and ^{130}Te. A rather simple nuclear Hamiltonian consisting of phenomenological mean field and zero-range residual particle-hole and particle-particle interaction is used. The calculated M^{2\nu} are almost not affected when the single-particle continuum is taken into account. At the same time, a regular suppression of the $0\nu\beta\beta$-amplitude is found that can be associated with additional ground state correlations due to collective states in the continuum. It is expected that future inclusion of the nucleon pairing in the single-particle continuum will somewhat compensate the suppression.Comment: 20 pages, 1 figure, published versio

The Weil-\'etale fundamental group of a number field II

We define the fundamental group underlying to Lichtenbaum's Weil-\'etale cohomology for number rings. To this aim, we define the Weil-\'etale topos as a refinement of the Weil-\'etale sites introduced in \cite{Lichtenbaum}. We show that the (small) Weil-\'etale topos of a smooth projective curve defined in this paper is equivalent to the natural definition given in \cite{Lichtenbaum-finite-field}. Then we compute the Weil-\'etale fundamental group of an open subscheme of the spectrum of a number ring. Our fundamental group is a projective system of locally compact topological groups, which represents first degree cohomology with coefficients in locally compact abelian groups. We apply this result to compute the Weil-\'etale cohomology in low degrees and to prove that the Weil-\'etale topos of a number ring satisfies the expected properties of the conjectural Lichtenbaum topos.Comment: 59 pages. To appear in Selecta Mathematic

Pre-Darwinian species change: reincarnation and transformism in George Sand’s Évenor et Leucippe

No abstract available