Goto

Collaborating Authors

 gradient descent step


481fbfa59da2581098e841b7afc122f1-Supplemental.pdf

Neural Information Processing Systems

The code for our experiments is available at https://github.com/AndyShih12/HyperSPN. To examine the merits of HyperSPNs as discussed in Section 3, we construct a hand-crafted dataset to test the three types of models described in Figure 4: SPN-Large, SPN-Small, and HyperSPN. The hand-crafted dataset is procedurally generated with 256 binary variables and 10000 instances, broken into train/valid/test splits at 70/10/20%. The generation procedure is designed such that the correlation between variable i and j is dependent on the path length between leaves i and j of a complete binary tree over the 256 variables. The exact details can be found in our code.


An equivalence between high dimensional Bayes optimal inference and M-estimation

Neural Information Processing Systems

When recovering an unknown signal from noisy measurements, the computational difficulty of performing optimal Bayesian MMSE (minimum mean squared error) inference often necessitates the use of maximum a posteriori (MAP) inference, a special case of regularized M-estimation, as a surrogate. However, MAP is suboptimal in high dimensions, when the number of unknown signal components is similar to the number of measurements. In this work we demonstrate, when the signal distribution and the likelihood function associated with the noise are both log-concave, that optimal MMSE performance is asymptotically achievable via another M-estimation procedure. This procedure involves minimizing convex loss and regularizer functions that are nonlinearly smoothed versions of the widely applied MAP optimization problem. Our findings provide a new heuristic derivation and interpretation for recent optimal M-estimators found in the setting of linear measurements and additive noise, and further extend these results to nonlinear measurements with non-additive noise. We numerically demonstrate superior performance of our optimal M-estimators relative to MAP. Overall, at the heart of our work is the revelation of a remarkable equivalence between two seemingly very different computational problems: namely that of high dimensional Bayesian integration underlying MMSE inference, and high dimensional convex optimization underlying M-estimation. In essence we show that the former difficult integral may be computed by solving the latter, simpler optimization problem.


A Hand-Crafted Example

Neural Information Processing Systems

The code for our experiments is available at https://github.com/AndyShih12/HyperSPN. To examine the merits of HyperSPNs as discussed in Section 3, we construct a hand-crafted dataset to test the three types of models described in Figure 4: SPN-Large, SPN-Small, and HyperSPN. The hand-crafted dataset is procedurally generated with 256 binary variables and 10000 instances, broken into train/valid/test splits at 70/10/20%. The generation procedure is designed such that the correlation between variable i and j is dependent on the path length between leaves i and j of a complete binary tree over the 256 variables. The exact details can be found in our code.


Appendix: VariationalContinualBayesian Meta-Learning

Neural Information Processing Systems

In variational continual learning, the posterior distribution of interest is frequently intractable and approximation is required. We summarize the meta-training process of our VC-BML in algorithm 1. Moreover,we evaluate FTML onthe unseen tasks (i.e., tasks sampled from meta-test set) instead ofthe training tasksthattheoriginalFTMLused. It would be unfair to adopt the original initialization procedure in OSML. BOMVI [10]: In our experiments, we use variational inference to approximate the posterior of meta-parameters. E.3.2 Settings As the latent variables in this paper are meta-parameters and task-specific parameters, the dimensionality ofthelatent space isactually determined bythenumber ofparameters inthedeep neural network. In particular, we define a CNN architecture and present its details in Table 1.



Robust Non-negative Proximal Gradient Algorithm for Inverse Problems

arXiv.org Machine Learning

Proximal gradient algorithms (PGA), while foundational for inverse problems like image reconstruction, often yield unstable convergence and suboptimal solutions by violating the critical non-negativity constraint. We identify the gradient descent step as the root cause of this issue, which introduces negative values and induces high sensitivity to hyperparameters. To overcome these limitations, we propose a novel multiplicative update proximal gradient algorithm (SSO-PGA) with convergence guarantees, which is designed for robustness in non-negative inverse problems. Our key innovation lies in superseding the gradient descent step with a learnable sigmoid-based operator, which inherently enforces non-negativity and boundedness by transforming traditional subtractive updates into multiplicative ones. This design, augmented by a sliding parameter for enhanced stability and convergence, not only improves robustness but also boosts expressive capacity and noise immunity. We further formulate a degradation model for multi-modal restoration and derive its SSO-PGA-based optimization algorithm, which is then unfolded into a deep network to marry the interpretability of optimization with the power of deep learning. Extensive numerical and real-world experiments demonstrate that our method significantly surpasses traditional PGA and other state-of-the-art algorithms, ensuring superior performance and stability.



Statistically guided deep learning

arXiv.org Machine Learning

We present a theoretically well-founded deep learning algorithm for nonparametric regression. It uses over-parametrized deep neural networks with logistic activation function, which are fitted to the given data via gradient descent. We propose a special topology of these networks, a special random initialization of the weights, and a data-dependent choice of the learning rate and the number of gradient descent steps. We prove a theoretical bound on the expected $L_2$ error of this estimate, and illustrate its finite sample size performance by applying it to simulated data. Our results show that a theoretical analysis of deep learning which takes into account simultaneously optimization, generalization and approximation can result in a new deep learning estimate which has an improved finite sample performance.


Review for NeurIPS paper: Consequences of Misaligned AI

Neural Information Processing Systems

Weaknesses: The theoretical setting makes quite strong assumptions, and doesn't really discuss the intuition behind them, so it would be easy for a cursory reader to infer that more is happening than really is. In particular, the various component-wise strict increase assumptions are doing a lot of work. Here are the various results translated into prose: Theorem 1: If moving in a particular direction D strictly increases the utility available from moving in other directions, an optimal agent will move as far as possible along D. Theorem 2: The only way moving arbitrarily far can't arbitrarily decrease utility is if one can move arbitrarily far without arbitrarily decreasing utility. Proposition 1: We can decrease utility by moving arbitrarily far if the boundary shape vs. utility slope has a certain shape. Proposition 2: If we fix some dimensions, we can compute utility ignoring the fixed dimensions. Proposition 3: An agent that is allowed to move arbitrarily far in one step is basically the same as a non-interactive agent.


One-Class Domain Adaptation via Meta-Learning

arXiv.org Artificial Intelligence

The deployment of IoT (Internet of Things) sensor-based machine learning models in industrial systems for anomaly classification tasks poses significant challenges due to distribution shifts, as the training data acquired in controlled laboratory settings may significantly differ from real-time data in production environments. Furthermore, many real-world applications cannot provide a substantial number of labeled examples for each anomalous class in every new environment. It is therefore crucial to develop adaptable machine learning models that can be effectively transferred from one environment to another, enabling rapid adaptation using normal operational data. We extended this problem setting to an arbitrary classification task and formulated the one-class domain adaptation (OC-DA) problem setting. We took a meta-learning approach to tackle the challenge of OC-DA, and proposed a task sampling strategy to adapt any bi-level meta-learning algorithm to OC-DA. We modified the well-established model-agnostic meta-learning (MAML) algorithm and introduced the OC-DA MAML algorithm. We provided a theoretical analysis showing that OC-DA MAML optimizes for meta-parameters that enable rapid one-class adaptation across domains. The OC-DA MAML algorithm is evaluated on the Rainbow-MNIST meta-learning benchmark and on a real-world dataset of vibration-based sensor readings. The results show that OC-DA MAML significantly improves the performance on the target domains and outperforms MAML using the standard task sampling strategy.