Federated Learning (FL) has been proposed as a privacy-preserving solution for distributed machine learning, particularly in heterogeneous FL settings where clients have varying computational capabilities and thus tra...
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Federated Learning (FL) has been proposed as a privacy-preserving solution for distributed machine learning, particularly in heterogeneous FL settings where clients have varying computational capabilities and thus train models with different complexities compared to the server's model. However, FL is not without vulnerabilities: recent studies have shown that it is susceptible to membership inference attacks (MIA), which can compromise the privacy of client data. In this paper, we examine the intersection of these two aspects, heterogeneous FL and its privacy vulnerabilities, by focusing on the role of client model integration, the process through which the server integrates parameters from clients' smaller models into its larger model. To better understand this process, we first propose a taxonomy that categorizes existing heterogeneous FL methods and enables the design of seven novel heterogeneous FL model integration strategies. Using CIFAR-10, CIFAR-100, and FEMNIST vision datasets, we evaluate the privacy and accuracy trade-offs of these approaches under three types of MIAs. Our findings reveal significant differences in privacy leakage and performance depending on the integration method. Notably, introducing randomness in the model integration process enhances client privacy while maintaining competitive accuracy for both the clients and the server. This work provides quantitative light on the privacy-accuracy implications client model integration in heterogeneous FL settings, paving the way towards more secure and efficient FL systems.
The research question we consider is whether incremental complexity in option pricing models is justified by incremental model performance. We apply the model confidence set as a formal model comparison approach in ap...
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The research question we consider is whether incremental complexity in option pricing models is justified by incremental model performance. We apply the model confidence set as a formal model comparison approach in appraising stochastic volatility jump-diffusion option pricing models, spanning affine and nonaffine specifications. Jumps in price with stochastic (constant) arrival intensity produce superior (inferior) outcomes. A parsimonious negative exponential price jump distribution outperforms the popular normal distribution. Jumps in volatility (synchronized or not) worsen model performance. A parsimonious nonlinear hyperbolic drift extension of the Heston model performs particularly well. Nonlinear CEV models generally do not produce appreciable model performance.
Biotic disturbances, i.e. ecosystem perturbations driven by insects and pathogens, are distinct from abiotic events in their duration, severity, and variable effects on carbon (C) pools and fluxes. Because of these fa...
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Biotic disturbances, i.e. ecosystem perturbations driven by insects and pathogens, are distinct from abiotic events in their duration, severity, and variable effects on carbon (C) pools and fluxes. Because of these factors and their interactions with climate, biotic disturbances present a substantial challenge to ecosystem modelers attempting to balance model complexity, accessibility, and realism. Here we share our recent experience with model-data fusion experiments as part of the Forest Resilience Threshold Experiment (FoRTE), using both a very simple and a highly complex model to simulate ecologically complex biotic disturbance responses. In this Viewpoint, our goals are to (1) synthesize our experiences with both models, weighing model complexity-process specificity trade-offs, and (2) suggest three priorities for future efforts to improve ecosystem modeling of biotic disturbance impacts to the terrestrial C cycle.
We present a discriminant measure that can be used to determine the model complexity in a speech recognition system. In the speech recognition process, sub-phonetic classes are modelled as mixtures of Gaussians, and i...
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We present a discriminant measure that can be used to determine the model complexity in a speech recognition system. In the speech recognition process, sub-phonetic classes are modelled as mixtures of Gaussians, and in this correspondence we present a new discriminant measure that uses the classification accuracy to determine in an objective fashion, the number of Gaussians required to best model the pdf of an allophone class. We compare the performance of this criterion with other criteria such as BIG, and show that BIC and the discriminative criterion lead to parsimonious models that provide the same word error rate performance as much larger baseline systems. However, this performance improvement depends on the size of the system, and there appears to be a crossover point beyond which both BIC and the discriminative criterion are worse than a much simpler criterion. The discriminative criterion also enables this crossover point to be controlled by means of a threshold that is used in the criterion, and can lead to a better tradeoff of complexity versus word error rate.
model complexity is a fundamental problem in deep learning. In this paper, we conduct a systematic overview of the latest studies on model complexity in deep learning. model complexity of deep learning can be categori...
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model complexity is a fundamental problem in deep learning. In this paper, we conduct a systematic overview of the latest studies on model complexity in deep learning. model complexity of deep learning can be categorized into expressive capacity and effective model complexity. We review the existing studies on those two categories along four important factors, including model framework, model size, optimization process, and data complexity. We also discuss the applications of deep learning model complexity including understanding model generalization, model optimization, and model selection and design. We conclude by proposing several interesting future directions.
This paper analyses how limits to the complexity of statistical models used by market participants can shape asset prices. We consider an economy in which the stochastic process that governs the evolution of economic ...
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This paper analyses how limits to the complexity of statistical models used by market participants can shape asset prices. We consider an economy in which the stochastic process that governs the evolution of economic variables may not have a simple representation, and yet, agents are only capable of entertaining statistical models with a certain level of complexity. As a result, they may end up with a lower-dimensional approximation that does not fully capture the intertemporal complexity of the true data-generating process. We first characterize the implications of the resulting departure from rational expectations and relate the extent of return and forecast-error predictability at various horizons to the complexity of agents' models and the statistical properties of the underlying process. We then apply our framework to study violations of uncovered interest rate parity in foreign exchange markets. We find that constraints on the complexity of agents' models can generate return predictability patterns that are simultaneously consistent with the well-known forward discount and predictability reversal puzzles.
This work deals with model complexity in clustering. Methods to control complexity in unsupervised learning are reviewed. A method that decouples the number of clusters from clustering model complexity is presented an...
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ISBN:
(纸本)9783319337470
This work deals with model complexity in clustering. Methods to control complexity in unsupervised learning are reviewed. A method that decouples the number of clusters from clustering model complexity is presented and its properties are discussed with the help of experiments on benchmark data sets.
In this paper, we propose a generalized fuzzy clustering regularization (GFCR) model and then study its theoretical properties. GFCR unifies several fuzzy clustering algorithms, such as fuzzy c-means (FCM), maximum en...
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In this paper, we propose a generalized fuzzy clustering regularization (GFCR) model and then study its theoretical properties. GFCR unifies several fuzzy clustering algorithms, such as fuzzy c-means (FCM), maximum entropy clustering (MEC), fuzzy clustering based on Fermi-Dirac entropy, and fuzzy bidirectional associative clustering network, etc. The proposed GFCR becomes an alternative model of the generalized FCM (GFCM) that was recently proposed by Yu and Yang. To advance theoretical study, we have the following three considerations. 1) We give an optimality test to monitor if GFCR converges to a local minimum. 2) We relate the GFCR optimality tests to Occam's razor principle, and then analyze the model complexity for fuzzy clustering algorithms. 3) We offer a general theoretical method to evaluate the performance of fuzzy clustering algorithms. Finally, some numerical experiments are used to demonstrate the validity of our theoretical results and complexity analysis.
Recent increases in computational power have led to the development of more advanced physically-based models which can handle a wide range of environmental processes. Although these models are very useful for increasi...
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Recent increases in computational power have led to the development of more advanced physically-based models which can handle a wide range of environmental processes. Although these models are very useful for increasing our understanding of unsaturated zone flow processes, their outputs usually contain high uncertainty, particularly when the level of complexity is not supported by observations. In this context, the aim of this paper is to compare the performance of three different model conceptualizations of a shallow unsaturated soil zone using the physically-based model HydroGeoSphere (HGS). To accomplish this task, we simulated actual evapotranspiration (ET), water content (WC) and discharge (D) from a weighing lysimeter for each of the conceptual models. Conceptual model 1 considers the lysimeter as a homogeneous zone with matrix flow, while Conceptual model 2 has an added preferential flow component. Conceptual model 3 includes layered heterogeneity in addition to the matrix and preferential flow components. The results indicated that the model performance in reproducing daily ET, WC and D improves when we move from simple models to more complex models. A comparison between event-based, monthly, seasonal and yearly time scales indicates that the simplest conceptual model is not reliable for reproducing event-based discharges. However, it can compete with more complex models at annual scales, although the uncertainty bound for the simple model is very high. While increasing complexity from the simplest to the more complex model leads to lower uncertainty bounds and more reliable values of the lysimeter discharge at monthly and seasonal time scales, uncertainty bounds became larger when complexity increased in the most complex model. This is related to a higher number of unknown model parameters in the calibration which are not supported by the available observation datasets. (C) 2015 Elsevier B.V. All rights reserved.
A brief study on the complexity of the structure of aircraft tyres is presented. The main goal is to investigate how complexity of Finite element (FE) models of the tyre can affect the simulation behaviour with respec...
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A brief study on the complexity of the structure of aircraft tyres is presented. The main goal is to investigate how complexity of Finite element (FE) models of the tyre can affect the simulation behaviour with respect to accurate prediction of real tyre behaviour. Three FE models, so called "simple", "regular" and "complex" were developed for this investigation so that the accuracy of results obtained from the models for different types of analysis can be determined in comparison with measured test data. For all the simulations carried out, including tyre burst test and tyre inflation, a hyperelastic material property was assumed for modelling rubber and cord materials, using the Yeoh model [1]. Simulations were performed using Abaqus/CAE for two dimensional (2D) analysis and Abaqus command line partly for three dimensional (3D) simulation of tyre inflation. Physical tests were carried out on two tyres for FE model validation in terms of tyre burst test and profile sizing measurements. The results showed excellent accuracy in terms of deformation in FE models by comparison with real size measurements of tyre profiles. Also, a quite good prediction of tyre burst pressure under high inflation was obtained for the different models. Finally, the investigation showed that while maximum stress in cords and maximum deflection of tyres at the rated inflation pressure were fairly insensitive to varying the mesh size in the FE models, maximum stress in the rubber components was particularly sensitive to such mesh size variation. (C) 2011 Elsevier Ltd. All rights reserved.
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