Search results for "Variable"
showing 10 items of 1674 documents
On the order of indeterminate moment problems
2013
For an indeterminate moment problem we denote the orthonormal polynomials by P_n. We study the relation between the growth of the function P(z)=(\sum_{n=0}^\infty|P_n(z)|^2)^{1/2} and summability properties of the sequence (P_n(z)). Under certain assumptions on the recurrence coefficients from the three term recurrence relation zP_n(z)=b_nP_{n+1}(z)+a_nP_n(z)+b_{n-1}P_{n-1}(z), we show that the function P is of order \alpha with 0<\alpha<1, if and only if the sequence (P_n(z)) is absolutely summable to any power greater than 2\alpha. Furthermore, the order \alpha is equal to the exponent of convergence of the sequence (b_n). Similar results are obtained for logarithmic order and for more ge…
Occlusion-based estimation of independent multinomial random variables using occurrence and sequential information
2017
Abstract This paper deals with the relatively new field of sequence-based estimation in which the goal is to estimate the parameters of a distribution by utilizing both the information in the observations and in their sequence of appearance. Traditionally, the Maximum Likelihood (ML) and Bayesian estimation paradigms work within the model that the data, from which the parameters are to be estimated, is known, and that it is treated as a set rather than as a sequence. The position that we take is that these methods ignore, and thus discard, valuable sequence -based information, and our intention is to obtain ML estimates by “extracting” the information contained in the observations when perc…
Selection of the Best Subset of Variables in Regression and Time Series Models
2009
The problem of variable selection is one of the most pervasive model selection problems in statistical applications. Often referred to as the problem of subset selection, it arises when one wants to model the relationship between a variable of interest and a subset of potential explanatory variables or predictors, but there is uncertainty about which subset to use. Several papers have dealt with various aspects of the problem but it appears that the typical regression user has not benefited appreciably. One reason for the lack of resolution of the problem is the fact that it is has not been well defined. Indeed, it is apparent that there is not a single problem, but rather several problems …
An Innovative Pricing Method for Telecommunication Services Pricing through American Options
2009
With the evolution of telecommunication networks and of their services the role of service provider is changed, so nowadays there is a coexistence of Network Operators and Virtual Operators. The difference between these players is not in the way they offer a service but primarily in their economic objectives and risk attitudes. Essentially, Network Operators own their infrastructures and typically have to sustain both fixed costs (CAPEX) and recurrent costs (OPEX), while Virtual Operators may have a simpler cost structure, mainly consisting of OPEX for the hire of network resources. Since these two operators can provide the same service in two different markets, their objectives differ subs…
Taste heterogeneity and latent preferences in the choice behaviour of freight transport operators
2013
In this paper we show that individual attitudes of road carriers and their latent preferences toward specific freight service attributes do play a role in determining their mode choices. Specifically, we contribute to the empirical literature on freight agents' mode choice by exploring the role of the "perceived importance" of the most relevant service dimensions in determining the attractiveness of two alternatives to "all-road" transport: logistics terminals and road-sea intermodal services. This is carried out through a revealed/stated preference experiment and a mixture of logit framework. Our results support the hypothesis that operators' attitudes towards time, punctuality and risk of…
TRAVELLING TOWARDS AND FROM MINOR ISLANDS THROUGH NON-CONVENTIONAL AIR TRANSPORT: DEMAND AND COST ANALYSIS
2010
This research addresses the role of innovative forms of passenger air transport in favouring mobility of tourists visiting minor islands. In particular, we studied the feasibility of scheduled transport services using helicopter and seaplane for connecting Sicily in the south of Italy, to the near and very attractive Eolie Islands rapidly. In order to estimate the potential service demand, we allowed for the number of tourists arriving in the Eolie Archipelago during the period 1999-2008. In detail, we considered only the market of visitors with a high willingness-to-pay for time savings (individuals choosing superior hotels) coming from origins at least 300 km away from the Eolie Islands. …
A New Multiblock PLS Based Method to Estimate Causal Models: Application to the Post-Consumption Behavior in Tourism
2009
This study presents a new algorithm for estimating causal models based on multiblock PLS method. This new algorithm is tested in a particular post-consumption behavior with the aim of validating a complex system of relations between antecedents of value, perceived value, satisfaction and loyalty. The results are compared with the classical LVPLS method: both methods support the proposed structural relations, but the explained variance is slightly higher with the new algorithm.
Semidirect products of internal groupoids
2010
We give a characterization of those finitely complete categories with initial object and pushouts of split monomorphisms that admit categorical semidirect products. As an application we examine the case of groupoids with fixed set of objects. Further, we extend this to the internal case. (C) 2010 Elsevier B.V. All rights reserved.
Nature log-analytique du volume des sous-analytiques
2000
Using a preparation theorem for subanalytic functions and Lipschitz stratification for compact subanalytic sets we prove that volumes of slices of globally subanalytic sets and density have a log-analytic nature. We also prove that the set of parameters for which the volume of fiber is finite is globally subanalytic.
Internal Time and Innovation
2003
Consider a physical system that may be observed through time-varying quantities x t , where t stands for time that may be discrete or continuous. The set x t may be a realization of a deterministic system, e.g. a unique solution of a differential equation, or a stochastic process. In the latter case each x t is a random variable. We are interested in the global evolution of the system, not particular realizations x t , from the point of view of innovation. We call the evolution innovative if the dynamics of the system is such that there is a gain of information about the system as time increases. Our purpose is to associate the concept of internal time with such systems. The internal time w…