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Alexander G. Gray

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

12 papers
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Possible papers

12

AAAI Conference 2025 Conference Paper

Neural Reasoning Networks: Efficient Interpretable Neural Networks with Automatic Textual Explanations

  • Stephen Carrow
  • Kyle Erwin
  • Olga Vilenskaia
  • Parikshit Ram
  • Tim Klinger
  • Naweed Khan
  • Ndivhuwo Makondo
  • Alexander G. Gray

Recent advances in machine learning have led to a surge in adoption of neural networks for various tasks, but lack of interpretability remains an issue for many others in which an understanding of the features influencing the prediction is necessary to ensure fairness, safety, and legal compliance. In this paper we consider one class of such tasks, tabular dataset classification, and propose a novel neuro-symbolic architecture, Neural Reasoning Networks (NRN), that is scalable and generates logically sound textual explanations for its predictions. NRNs are connected layers of logical neurons that implement a form of real valued logic. A training algorithm (R-NRN) learns the weights of the network as usual using gradient descent optimization with backprop, but also learns the network structure itself using a bandit-based optimization. Both are implemented in an extension to PyTorch that takes full advantage of GPU scaling and batched training. Evaluation on a diverse set of 22 open-source datasets for tabular classification demonstrates performance (measured by ROC AUC) which improves over Multilayer Perceptron (MLP) and is statistically similar to other state-of-the-art approaches such as Random Forest, XGBoost and Gradient Boosted Trees, while offering 43% faster training and a more than 2 orders of magnitude reduction in the number of parameters required, on average. Furthermore, R-NRN explanations are shorter than the compared approaches while producing more accurate feature importance scores.

IJCAI Conference 2024 Conference Paper

What Makes Models Compositional? A Theoretical View

  • Parikshit Ram
  • Tim Klinger
  • Alexander G. Gray

Compositionality is thought to be a key component of language, and various compositional benchmarks have been developed to empirically probe the compositional generalization of existing sequence processing models. These benchmarks often highlight failures of existing models, but it is not clear why these models fail in this way. In this paper, we seek to theoretically understand the role the compositional structure of the models plays in these failures and how this structure relates to their expressivity and sample complexity. We propose a general neuro-symbolic definition of compositional functions and their compositional complexity. We then show how various existing general and special purpose sequence processing models (such as recurrent, convolution and attention-based ones) fit this definition and use it to analyze their compositional complexity. Finally, we provide theoretical guarantees for the expressivity and systematic generalization of compositional models that explicitly depend on our proposed definition and highlighting factors which drive poor empirical performance.

UAI Conference 2013 Conference Paper

Building Bridges: Viewing Active Learning from the Multi-Armed Bandit Lens

  • Ravi Ganti
  • Alexander G. Gray

In this paper we propose a multi-armed bandit inspired, pool based active learning algorithm for the problem of binary classification. By carefully constructing an analogy between active learning and multi-armed bandits, we utilize ideas such as lower confidence bounds, and self-concordant regularization from the multi-armed bandit literature to design our proposed algorithm. Our algorithm is a sequential algorithm, which in each round assigns a sampling distribution on the pool, samples one point from this distribution, and queries the oracle for the label of this sampled point. The design of this sampling distribution is also inspired by the analogy between active learning and multi-armed bandits. We show how to derive lower confidence bounds required by our algorithm. Experimental comparisons to previously proposed active learning algorithms show superior performance on some standard UCI data-sets.

JMLR Journal 2013 Journal Article

MLPACK: A Scalable C++ Machine Learning Library

  • Ryan R. Curtin
  • James R. Cline
  • N. P. Slagle
  • William B. March
  • Parikshit Ram
  • Nishant A. Mehta
  • Alexander G. Gray

MLPACK is a state-of-the-art, scalable, multi-platform C++ machine learning library released in late 2011 offering both a simple, consistent API accessible to novice users and high performance and flexibility to expert users by leveraging modern features of C++. MLPACK provides cutting-edge algorithms whose benchmarks exhibit far better performance than other leading machine learning libraries. MLPACK version 1.0.3, licensed under the LGPL, is available at www.mlpack.org. [abs] [ pdf ][ bib ] [ code ] &copy JMLR 2013. ( edit, beta )

ICML Conference 2013 Conference Paper

Sparsity-Based Generalization Bounds for Predictive Sparse Coding

  • Nishant A. Mehta
  • Alexander G. Gray

The goal of predictive sparse coding is to learn a representation of examples as sparse linear combinations of elements from a dictionary, such that a learned hypothesis linear in the new representation performs well on a predictive task. Predictive sparse coding has demonstrated impressive performance on a variety of supervised tasks, but its generalization properties have not been studied. We establish the first generalization error bounds for predictive sparse coding, in the overcomplete setting, where the number of features k exceeds the original dimensionality d. The learning bound decays as (sqrt(d k/m)) with respect to d, k, and the size m of the training sample. It depends intimately on stability properties of the learned sparse encoder, as measured on the training sample. Consequently, we also present a fundamental stability result for the LASSO, a result that characterizes the stability of the sparse codes with respect to dictionary perturbations.

ICML Conference 2013 Conference Paper

Stochastic Alternating Direction Method of Multipliers

  • Hua Ouyang
  • Niao He
  • Long Q. Tran
  • Alexander G. Gray

The Alternating Direction Method of Multipliers (ADMM) has received lots of attention recently due to the tremendous demand from large-scale and data-distributed machine learning applications. In this paper, we present a stochastic setting for optimization problems with non-smooth composite objective functions. To solve this problem, we propose a stochastic ADMM algorithm. Our algorithm applies to a more general class of convex and nonsmooth objective functions, beyond the smooth and separable least squares loss used in lasso. We also demonstrate the rates of convergence for our algorithm under various structural assumptions of the stochastic function: O(1/\sqrtt) for convex functions and O(\log t/t) for strongly convex functions. Compared to previous literature, we establish the convergence rate of ADMM for convex problems in terms of both the objective value and the feasibility violation. A novel application named Graph-Guided SVM is proposed to demonstrate the usefulness of our algorithm.

ICML Conference 2013 Conference Paper

Tree-Independent Dual-Tree Algorithms

  • Ryan R. Curtin
  • William B. March
  • Parikshit Ram
  • David V. Anderson
  • Alexander G. Gray
  • Charles Isbell

Dual-tree algorithms are a widely used class of branch-and-bound algorithms. Unfortunately, developing dual-tree algorithms for use with different trees and problems is often complex and burdensome. We introduce a four-part logical split: the tree, the traversal, the point-to-point base case, and the pruning rule. We provide a meta-algorithm which allows development of dual-tree algorithms in a tree-independent manner and easy extension to entirely new types of trees. Representations are provided for five common algorithms; for k-nearest neighbor search, this leads to a novel, tighter pruning bound. The meta-algorithm also allows straightforward extensions to massively parallel settings.

UAI Conference 2006 Conference Paper

Faster Gaussian Summation: Theory and Experiment

  • Dongryeol Lee
  • Alexander G. Gray

We provide faster algorithms for the problem of Gaussian summation, which occurs in many machine learning methods. We develop two new extensions - an O(Dp) Taylor expansion for the Gaussian kernel with rigorous error bounds and a new error control scheme integrating any arbitrary approximation method - within the best discretealgorithmic framework using adaptive hierarchical data structures. We rigorously evaluate these techniques empirically in the context of optimal bandwidth selection in kernel density estimation, revealing the strengths and weaknesses of current state-of-the-art approaches for the first time. Our results demonstrate that the new error control scheme yields improved performance, whereas the series expansion approach is only effective in low dimensions (five or less).

v2026.09.13