1,789 research outputs found

    On the Approximation and Complexity of Deep Neural Networks to Invariant Functions

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    Recent years have witnessed a hot wave of deep neural networks in various domains; however, it is not yet well understood theoretically. A theoretical characterization of deep neural networks should point out their approximation ability and complexity, i.e., showing which architecture and size are sufficient to handle the concerned tasks. This work takes one step on this direction by theoretically studying the approximation and complexity of deep neural networks to invariant functions. We first prove that the invariant functions can be universally approximated by deep neural networks. Then we show that a broad range of invariant functions can be asymptotically approximated by various types of neural network models that includes the complex-valued neural networks, convolutional neural networks, and Bayesian neural networks using a polynomial number of parameters or optimization iterations. We also provide a feasible application that connects the parameter estimation and forecasting of high-resolution signals with our theoretical conclusions. The empirical results obtained on simulation experiments demonstrate the effectiveness of our method

    Towards Understanding Theoretical Advantages of Complex-Reaction Networks

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    Complex-valued neural networks have attracted increasing attention in recent years, while it remains open on the advantages of complex-valued neural networks in comparison with real-valued networks. This work takes one step on this direction by introducing the \emph{complex-reaction network} with fully-connected feed-forward architecture. We prove the universal approximation property for complex-reaction networks, and show that a class of radial functions can be approximated by a complex-reaction network using the polynomial number of parameters, whereas real-valued networks need at least exponential parameters to reach the same approximation level. For empirical risk minimization, our theoretical result shows that the critical point set of complex-reaction networks is a proper subset of that of real-valued networks, which may show some insights on finding the optimal solutions more easily for complex-reaction networks

    Evolution and focal features of China’s agricultural green development policies: Text analysis based on attention perspective

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    [Objective] Green development is an important direction for the structural reform and transformation and upgrading of modern agriculture. Exploring the evolution of government attention to policies on agricultural green development can provide theoretical references for future policy formulation and implementation. [Methods] From the perspective of attention, combined with the theoretical model of punctuated equilibrium, this study applied text mining methods such as high-frequency word identification, co-occurrence word analysis, and keyword clustering through Python to analyze 1535 policy documents related to agricultural green development from 1984 to 2022. [Results] The study found that: (1) From the historical evolution of attention allocation, it can be seen that China’s agricultural green development policies have experienced three stages: exploration, construction, and consolidation and deepening. There were differences in the focus of government attention to agricultural green development policies in different periods; leading enterprises were important subjects for promoting agricultural transformation, upgrading, and green development. (2) From the perspective of focus configuration, China’s agricultural green development began with a top-down system engineering aimed at protecting the ecological environment. Technological innovation ran through the entire process of government attention to agricultural green development, and was the fundamental driving force for agricultural transformation, upgrading, and green development. [Conclusion] With the proposal of the rural revitalization strategy, the economic benefits in the process of agricultural green development are becoming increasingly prominent, and local governments should actively explore new paths and new methods of the integration of agricultural production and agricultural tourism under the premise of meeting the needs of ecological civilization construction, and take leading enterprises as the traction to help the industrialized operation of households in rural areas, and boost the green transformation and upgrading of China’s agriculture and high-quality development
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