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A Bi-Level Framework for Learning to Solve Combinatorial Optimization on Graphs

Neural Information Processing Systems

Combinatorial Optimization (CO) has been a long-standing challenging research topic featured by its NP-hard nature. Traditionally such problems are approximately solved with heuristic algorithms which are usually fast but may sacrifice the solution quality. Currently, machine learning for combinatorial optimization (MLCO) has become a trending research topic, but most existing MLCO methods treat CO as a single-level optimization by directly learning the end-to-end solutions, which are hard to scale up and mostly limited by the capacity of ML models given the high complexity of CO. In this paper, we propose a hybrid approach to combine the best of the two worlds, in which a bi-level framework is developed with an upper-level learning method to optimize the graph (e.g.


Credit Assignment in Neural Networks through Deep Feedback Control

Neural Information Processing Systems

The success of deep learning sparked interest in whether the brain learns by using similar techniques for assigning credit to each synaptic weight for its contribution to the network output. However, the majority of current attempts at biologically-plausible learning methods are either non-local in time, require highly specific connectivity motifs, or have no clear link to any known mathematical optimization method. Here, we introduce Deep Feedback Control (DFC), a new learning method that uses a feedback controller to drive a deep neural network to match a desired output target and whose control signal can be used for credit assignment. The resulting learning rule is fully local in space and time and approximates Gauss-Newton optimization for a wide range of feedback connectivity patterns. To further underline its biological plausibility, we relate DFC to a multi-compartment model of cortical pyramidal neurons with a local voltage-dependent synaptic plasticity rule, consistent with recent theories of dendritic processing. By combining dynamical system theory with mathematical optimization theory, we provide a strong theoretical foundation for DFC that we corroborate with detailed results on toy experiments and standard computer-vision benchmarks.


Understanding Instance-based Interpretability of Variational Auto-Encoders

Neural Information Processing Systems

Instance-based interpretation methods have been widely studied for supervised learning methods as they help explain how black box neural networks predict. However, instance-based interpretations remain ill-understood in the context of unsupervised learning. In this paper, we investigate influence functions [Koh and Liang, 2017], a popular instance-based interpretation method, for a class of deep generative models called variational auto-encoders (VAE). We formally frame the counter-factual question answered by influence functions in this setting, and through theoretical analysis, examine what they reveal about the impact of training samples on classical unsupervised learning methods. We then introduce VAE-TracIn, a computationally efficient and theoretically sound solution based on Pruthi et al. [2020], for VAEs. Finally, we evaluate VAE-TracIn on several real world datasets with extensive quantitative and qualitative analysis.





A More Related Work

Neural Information Processing Systems

There have been some efforts trying to improve contrastive learning from various perspectives, e.g., Our method adopts a similar idea to the CL setting to address one missing piece of the framework . 's are independent with each other given the similarity scores. The max-margin contrastive loss is defined on pair-wise data, thus is less affected by the negative samples. However, the loss is shown to be less effective compared to the fully coupled NT -Xent loss [13]. Please refer to the "Simulation" paragraph in Section 2.2.3 for details Thus, it is feasible to evaluate. For clearness, we redefine some terms used in our proof.



Unifying Activation-and Timing-based Learning Rules for Spiking Neural Networks Jinseok Kim 1 Kyungsu Kim

Neural Information Processing Systems

In this context, several studies have reported promising results with the gradient-based supervised learning methods that takes account of those characteristics [8-13]. Previous works on gradient-based supervised learning for SNNs can be classified into two categories.