A simple characterisation for sustained growth

This article considers an inter-temporal optimisation problem in a general form and gives conditions ensuring the convergence to infinity of the economy. These conditions can be easily verified and applied for a large class of problems in the literature. Some applications for different economies are given as illustrative examples.     

On a simple sequential decision problem

We consider a simple sequential problem that generalizes the gamble with a fair coin. A sequence [ X _n] ot {0,1} r.v.'s is observed, and at each step the gambler can bet on either 0 or 1. The sequence ( X _n) is assumed exchangeable. Except for the case of i.i.d. r.v.'s with even probability (the fair coin), there exists a strategy such that the cumulated expected gain diverges to +∞.     

On the dynamic response of a firm to an employment subsidy with a fmd threshold

During the last two decades, policy-makers have included employment subsidies among the tools of stabilization policy. Employment subsidy programs have been introduced in Japan, Great Britain, Europe and the United States. There has been some concern, however, about the effectiveness of such programs. In this paper, we analyze how a profit-maximizing firm will respond to a marginal subsidy program with a fixed threshold, focusing on the role of inventories. We show that, in some cases, the firm may have an incentive to manipulate inventories in a way that increases its profits but lowers the cost effectiveness of the program.     

Satisficing with a variable threshold

We axiomatize a model of satisficing which features random thresholds and the possibility of choice abstention. Given a menu, the decision maker first randomly draws a threshold. Next, using a list order, she searches the menu for alternatives which are at least as good as the threshold. She chooses the first such alternative she finds, and if no such alternative exists, she abstains. Since the threshold is random, so is the resulting behavior. We characterize this model using two simple axioms. In general the revelation of the model’s primitives is incomplete. We characterize a specialization of the model for which the underlying preference and list ordering are uniquely identified by choice frequencies. We also show that our model is a special Random Utility Model.     

On corporate structure,strategy, and performance: a study with directed acyclic graphs and PC algorithm

This paper reconsiders empirical evidence on relationships among variables related to corporate strategy, structure, and performance. Causal relationships among variables are modeled as directed acyclic graphs using PC‐algorithm. Return on Assets appears to be determined by Advertising Intensity, Unrelated Diversification, R&D Intensity, and Organizational Ownership Hierarchy. Debt Structure and Investor Characteristics do not cause (either directly or indirectly) return on assets. These latter two variables appear to be effects of return on assets, not causes. Results offer mixed support of the theory that structure causes strategy, which in turn causes performance. Copyright © 2009 John Wiley & Sons, Ltd.     

On sooner and later waiting time distributions associated with simple patterns in a sequence of bivariate trials

In this article, we study sooner/later waiting time problems for simple patterns in a sequence of bivariate trials. The double generating functions of the sooner/later waiting times for the simple patterns are expressed in terms of the double generating functions of the numbers of occurrences of the simple patterns. Effective computational tools are developed for the evaluation of the waiting time distributions along with some examples. The results presented here provide perspectives on the waiting time problems arising from bivariate trials and extend a framework for studying the exact distributions of patterns. Finally, some examples are given in order to illustrate how our theoretical results are employed for the investigation of the waiting time problems for simple patterns.     

Disconnecting graphs by removing vertices: a polyhedral approach

In this paper, we consider the problem of disconnecting a graph by removing as few vertices as possible, such that no component of the disconnected graph has more than a given number of vertices. We give applications of this problem, present a formulation for it, and describe some polyhedral results. Furthermore, we establish ties with other polytopes and show how these relations can be used to obtain facets of our polytope. Finally, we give some computational results.     

Agent based model of a simple economy

This article proposes a model of a simple economy based on a set of agent-based modeling principles. The model is based on the ??trust game?? formulated by Berg et?al. (Games Econ Behav 10:122?C142, 1995), and anticipates a random matching of partners taking in to account adaptive agent behavior. Simulation in the NetLogo programming environment, using profile distributions obtained from empirical studies, has shown the most successful agents to posses low parameters of trust in the role of Sender and high parameters of trustworthiness in the role of Receiver.     

Accuracy of proportion estimators: a simple rule

We consider the sample survey type problem of estimating the proportionp of a finite population of sizeN having a given attribute by the proportion of successes in a random sample (with or without replacement) of sizer from the population. Our main result indicates that is always at least a 91.0% confidence interval (C.I.) for the parameterp. We show that is at least as large under the hypergeometric model of simple random sampling without replacement as it is under the corresponding binomial model of random sampling with replacement. The significance of our main result is that it is a good, easily stated accuracy rule, holding for allr, N, andp, which can easily be understood by the layman when assessing accuracy of the estimator and discussing the relationship between accuracy and sample size.     

The valuation of barrier options under a threshold rough Heston model

In this paper, we propose a novel model for pricing double barrier options, where the asset price is modeled as a threshold geometric Brownian motion time changed by an integrated activity rate process, which is driven by the convolution of a fractional kernel with the CIR process. The new model both captures the leverage effect and produces rough paths for the volatility process. The model also nests the threshold diffusion, Heston and rough Heston models. We can derive analytical formulas for the double barrier option prices based on the eigenfunction expansion method. We also implement the model and numerically investigate the sensitivities of option prices with respect to the parameters of the model.     

Toward a simple structure: a comparison of different rotation techniques

This paper thematise the problem of seeking and devising a simple structure, when the solution envisages the extraction of more than one component or factor. To this avail, we shall make a comparison between a number of rotation techniques, both orthogonal and oblique, to evaluate just how capable they are of delivering the highest possible semplification of the data yielded by the analysis. To evaluate the results obtained through empirical controls, we have drawn up a simple structure index. For reasons of space, we shall apply principal components analysis to our method, although the results obtained here also hold for factor analysis.     

Estimation in threshold autoregressive models with a stationary and a unit root regime

This paper treats estimation in a class of new nonlinear threshold autoregressive models with both a stationary and a unit root regime. Existing literature on nonstationary threshold models has basically focused on models where the nonstationarity can be removed by differencing and/or where the threshold variable is stationary. This is not the case for the process we consider, and nonstandard estimation problems are the result.     

浅谈聚合物改性沥青的研究进展

文章回顾了近几十年来聚合物改性沥青的研究进展,从聚合物选择、试验方法和评价方法等方面进行了系统的述评,对存在的主要问题进行了全面总结,初步提出了解决的方法和技术途径。     

An investigation of the parameters of a simple mean-field model

In a recent work Gallo et al. (Math Models Methods Appl. Sci. 19:1427–1439, 2009) examined the parameters for a simple mean-field model of social interactions. Their work presented the model, raw data and parameter estimates with associated confidence intervals for a 4-year period. Here the problem is re-examined in greater mathematical detail and associated estimates evaluated. In particular exact results are obtained for a selection of any 3 years and parameters estimated for a 7-year period, the full extent of the data.     

The effects of input control in a simple scheduling model

Input control is a generic procedure for smoothing production workload by delaying work during intervals of heavy load. While input control techniques have several practical benefits, they also have an inherent disadvantage. By restricting the set of jobs available for scheduling, an input control procedure removes some of the scheduling options that would otherwise be available. This paper examines the impact of such a procedure in a simple simulation model.The simulation model represents a production shop in a simplified way, as a single machine, but the production control system has three distinct parts. The first part assigns due-dates to customer orders, taking into consideration the size of each job and the workload in the shop. The second part is a job releasing rule that implements input control. The third part is a priority dispatching procedure that is aimed at meeting due-dates. By representing this three-part control system the model provides an opportunity to explore the interdependence between input control and other control procedures.Reinforcing previous research, the simulation experiments confirm that modified due-date priorities perform more effectively than other basic priority rules when performance is measured by average tardiness. Moreover, the experiments indicate that performance under the modified due-date regime is never improved by the use of input control. On the other hand, with dispatching rules that rely on shortest-first or critical ratio priorities, the experiments indicate that input control is sometimes advantageous. The effects of input control on scheduling performance thus appear to be somewhat complicated, and further experiments were designed to explore some of the relationships involved. The principal finding, however, provides a warning that input control can be counterproductive.