33,057 research outputs found
Location equivalence in a parametric setting
AbstractLocation equivalence has been presented in [5] as a bisimulation-based equivalence able to take into account the spatial distribution of processes.In this work, the parametric approach of [12] is applied to location equivalence. An observation domain for localities is identified and the associated equivalence is shown to coincide with the equivalence introducted in [6,16]. The observation of a computation is a forest (defined up to isomorphism) whose nodes are the events (labeled by observable actions) and where the arcs describe the sublocation relation.We show in the paper that our approach is really parametric. By performing minor changes in the definitions, many equivalences are captured: partial and mixed ordering causal semantics, interleaving, and a variation of location equivalence where the generation ordering is not evidenced. It seems difficult to modify the definitions of [6,16] to obtain the last observation. The equivalence induced by this observation corresponds to the very intuitive assumption that different locations cannot share a common clock, and hence the ordering between events occurring in different places cannot be determined.Thanks to the general results proved in [12] for the parametric approach, all the observation equivalences described in this paper come equipped with sound and complete axiomatizations
Semi-parametric Models for Satisfaction with Income
An overview is presented of some parametric and semi-parametric models, estimators, and specification tests that can be used to analyze ordered response variables.In particular, limited dependent variable models that generalize or-dered probit are compared to regression models that generalize the linear model.These techniques are then applied to analyze how self-reported satisfaction with household income relates to household income, family composition, and other background variables.Data are drawn from the 1998 wave of the German Socio-Economic Panel.The results are used to estimate equivalence scales and the cost of children.We find that the standard ordered probit model is rejected, while some semi-parametric specifications survive specification tests against nonpara-metric alternatives.The estimated equivalence scales, however, are often similar for the parametric and semi-parametric specifications.incomes;semiparametric estimation;satisfaction
Language Emptiness of Continuous-Time Parametric Timed Automata
Parametric timed automata extend the standard timed automata with the
possibility to use parameters in the clock guards. In general, if the
parameters are real-valued, the problem of language emptiness of such automata
is undecidable even for various restricted subclasses. We thus focus on the
case where parameters are assumed to be integer-valued, while the time still
remains continuous. On the one hand, we show that the problem remains
undecidable for parametric timed automata with three clocks and one parameter.
On the other hand, for the case with arbitrary many clocks where only one of
these clocks is compared with (an arbitrary number of) parameters, we show that
the parametric language emptiness is decidable. The undecidability result
tightens the bounds of a previous result which assumed six parameters, while
the decidability result extends the existing approaches that deal with
discrete-time semantics only. To the best of our knowledge, this is the first
positive result in the case of continuous-time and unbounded integer
parameters, except for the rather simple case of single-clock automata
Semiparametric estimation of equivalence scales using subjective information
Household equivalence scales are not identified from consumer demand data alone. We estimate household equivalence scales using two types of subjective information. First, we use the answers to questions on the income required to attain a given utility level. This is the type of information often used in this type of research. We compare the results for the usual linear model with semiparametric estimates, in which the functional form of the relationship between required income and family size and actual income is left unspecified. Second, we use answers to the question: how satisfied are you with actual household income? We present parametric and semiparametric estimates for the ordered response model explaining this discrete variable, which has possible outcomes 1,2,...,10. We find that according to the second type of information, costs of children are much larger than according to the first.Household Economics;microeconomics
Class-Based Feature Matching Across Unrestricted Transformations
We develop a novel method for class-based feature matching across large changes in viewing conditions. The method is based on the property that when objects share a similar part, the similarity is preserved across viewing conditions. Given a feature and a training set of object images, we first identify the subset of objects that share this feature. The transformation of the feature's appearance across viewing conditions is determined mainly by properties of the feature, rather than of the object in which it is embedded. Therefore, the transformed feature will be shared by approximately the same set of objects. Based on this consistency requirement, corresponding features can be reliably identified from a set of candidate matches. Unlike previous approaches, the proposed scheme compares feature appearances only in similar viewing conditions, rather than across different viewing conditions. As a result, the scheme is not restricted to locally planar objects or affine transformations. The approach also does not require examples of correct matches. We show that by using the proposed method, a dense set of accurate correspondences can be obtained. Experimental comparisons demonstrate that matching accuracy is significantly improved over previous schemes. Finally, we show that the scheme can be successfully used for invariant object recognition
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