New analytic estimates for efficiency and vulnerability in the Erds-Rnji model are presented using probabilistic properties and diameter bounds that are specific for this model and its topology. These estimates for ra...
详细信息
New analytic estimates for efficiency and vulnerability in the Erds-Rnji model are presented using probabilistic properties and diameter bounds that are specific for this model and its topology. These estimates for random networks improve the known deterministic lower estimates for efficiency and vulnerability. The probabilistic technique provides a sharper approach to parametric analysis of random networks and allows us to report some new results concerning the efficiency-vulnerability relationship. Several numerical tests are presented to compare the lower estimates obtained with the empirical Erds-Rnji random networks. These estimates illustrate how the new probabilistic estimates improve on the generic estimates reported in the literature.
Mathematical models of meiosis that relate offspring to parental genotypes through parameters such as meiotic recombination frequency have been difficult to develop for polyploids. Existing models have limitations wit...
详细信息
Mathematical models of meiosis that relate offspring to parental genotypes through parameters such as meiotic recombination frequency have been difficult to develop for polyploids. Existing models have limitations with respect to their analytic potential, their compatibility with insights into mechanistic aspects of meiosis, and their treatment of model parameters in terms of parameter dependencies. In this article I put forward a computational approach to the probabilistic modeling of meiosis. A computer program enumerates all possible paths through the phases of replication, pairing, recombination, and segregation, while keeping track of the probabilities of the paths according to the various parameters involved. Probabilities for classes of genotypes or phenotypes are added, and the resulting formulas are simplified by the symbolic-computation system Mathematica. An example application to autotetraploids results in a model that remedies the limitations of previous models mentioned above. In addition to the immediate implications, the computational approach presented here can be expected to be useful through opening avenues for modeling a host of processes, including meiosis in higher-order ploidies.
The slow recovery of many developed economies to the recent financial crisis, and the largest fall in aggregate demand since WWII caused by the COVID-19 Pandemic with its foreseeable negative and persistent effects on...
详细信息
The slow recovery of many developed economies to the recent financial crisis, and the largest fall in aggregate demand since WWII caused by the COVID-19 Pandemic with its foreseeable negative and persistent effects on the aggregate supply, has generated renewed interest in the subject of hysteresis. The presence of significant hysteresis effects has important theoretical and policy implications. First, there is no unique and predetermined long-run equilibrium level of aggregate employment, as the equilibrium is permanently changed by temporary shocks. Second, as the economic system is not self-adjusting, substantial, timely, and sustained expansionary monetary and fiscal policy should be applied to mitigate the impact of shocks, including the temporary ones. Although it is not possible to quantify hysteresis effects in real time, we can use historical data to shed some light on the possible long-term economic consequences of the COVID-19 pandemic. For that purpose, we use the linear play-hysteresis model in the context of two equation system to analyses the join hysterical dynamics of aggregate employment and investment. We implement the model empirically by means of a new algorithm for the simultaneous equations system applied to Portuguese data that separates the effects of large and small changes in aggregate demand on aggregate employment and investment using an endogenous determined switching parameter as reference.
作者:
Mota, P. R.Vasconcelos, P. B.Univ Porto
Fac Econ Ctr Econ & Finance Rua Dr Roberto Frias S-N P-4200464 Porto Portugal Univ Porto
Fac Econ Ctr Math Rua Dr Roberto Frias S-N P-4200464 Porto Portugal
This paper proposes a new way of testing the effect of labor market reforms in the employment adjustment at the macro level. Following the approach to hysteresis based on the presence of non-convex costs of adjustment...
详细信息
This paper proposes a new way of testing the effect of labor market reforms in the employment adjustment at the macro level. Following the approach to hysteresis based on the presence of non-convex costs of adjustment, a switching aggregate employment equation is estimated, with an unknown splitting factor, from a computational implementation of the linear play hysteresis operator. The play hysteresis operator describes a dynamics where non-convex adjustment costs create intervals of weak reaction of employment to small variations in forcing variables, while spurts in employment adjustment may occur as a consequence of a large, or cumulative small shocks. The main contribution of this paper is to extend an existing approach for the case where there are disruptive breaks, by accommodating changes in the value of the switching parameter of the employment equation whenever labor market reforms are present. Numerical experiments on the Portuguese economy are performed.
We provide a "shared axiomatization" of natural numbers and hereditarily finite sets built around a polymorphic abstraction of bijective base-2 arithmetics. The "axiomatization" is described as a p...
详细信息
ISBN:
(纸本)9783642141270
We provide a "shared axiomatization" of natural numbers and hereditarily finite sets built around a polymorphic abstraction of bijective base-2 arithmetics. The "axiomatization" is described as a progressive refinement of Haskell type classes with examples of instances converging to an efficient implementation in terms of arbitrary length integers and bit operations. As an instance, we derive algorithms to perform arithmetic operations efficiently directly with hereditarily finite sets. The self-contained source code of the paper is available at http://***/tarau/research/2010/***
Pseudoinverses are ubiquitous tools for handling over- and under-determined systems of equations. For computational efficiency, sparse pseudoinverses are desirable. Recently, sparse left and right pseudoinverses were ...
详细信息
Pseudoinverses are ubiquitous tools for handling over- and under-determined systems of equations. For computational efficiency, sparse pseudoinverses are desirable. Recently, sparse left and right pseudoinverses were introduced, using 1-norm minimization and linear programming. We introduce several new sparse generalized inverses by using 1-norm minimization on a subset of the linear Moore-Penrose properties, again leading to linear programming. computationally, we demonstrate the usefulness of our approach in the context of application to least-squares problems and minimum 2-norm problems. One of the Moore-Penrose properties is nonlinear (in fact, quadratic), and so developing an effective convex relaxation for it is nontrivial. We develop a variety of methods for this, in particular a nonsymmetric lifting which is more efficient than the usual symmetric lifting that is normally applied to non-convex quadratic equations. In this context, we develop a novel and computationally effective âdiving procedureâ to find a path of solutions trading off sparsity against the nice properties of the Moore- Penrose pseudoinverse. Next, we consider the well-known low-rank/sparse decomposition problem min {
Great strides have been made in recent years in the search for ever larger prime Generalized Fermat Numbers (GFN). We briefly review the history of the GFN prime search, and describe new implementations of the 'Ge...
详细信息
ISBN:
(纸本)9783642552243
Great strides have been made in recent years in the search for ever larger prime Generalized Fermat Numbers (GFN). We briefly review the history of the GFN prime search, and describe new implementations of the 'Genefer' software (now available as open source) using CUDA and optimised CPU assembler which have underpinned this unprecedented progress. The results of the ongoing search are used to extend Gallot and Dubner's published tables comparing the theoretical predictions with actual distributions of primes, and we report on recent discoveries of GFN primes with over one million digits.
The rapid expansion of artificial intelligence (AI) areas and applications has become an everyday social reality and the development of computing methods and of technology, in order to accomplish for the respective ne...
详细信息
ISBN:
(纸本)9783031652226;9783031652233
The rapid expansion of artificial intelligence (AI) areas and applications has become an everyday social reality and the development of computing methods and of technology, in order to accomplish for the respective needs, emerge as one of the biggest challenges of this century. However, a strong background in mathematics and Statistical fundamentals is crucial to foster the robustness of AI Systems and to attain for the correspondent generalization capabilities. Thus, recognizing the importance and benefits of integrate multiple mathematical methodologies that can leverage the unique strengths of each to create synergistic effects, is here discussed. In the literature it is possible to find diverse connections of Mathematical and Statistical frameworks with AI Systems and Computing. For illustration: Algebra - can be used to manipulate data in high-dimensional spaces;Statistical Analysis - helps on providing confidence in decision-making;Linear Regression- can be used on data modelling and accuracy assessment;and Bayesian statistics - can be used in probabilistic programming for AI applications. This work particularly highlights the evolving role of Hadamard Matrices and Coding Theory, illustrating their synergy with AI Systems and Computing, and how such synergy is driving innovation in various fields and approaching the new reality of Quantic paradigms.
Provides a historical perspective on the interface of computer science and statistics. Country tracing the connection between the two professions; Mathematician making substantial contributions to computer science and...
详细信息
Provides a historical perspective on the interface of computer science and statistics. Country tracing the connection between the two professions; Mathematician making substantial contributions to computer science and statistics; Evolution of the interface.
暂无评论