Learning Signal Temporal Logic through Neural Network for Interpretable Classification

TL;DR

This paper introduces an explainable neural-symbolic framework that learns Signal Temporal Logic formulas for time-series classification, enhancing interpretability and efficiency over existing methods.

Contribution

It proposes a novel neural-STL framework with new time and softmax functions for efficient, accurate, and interpretable time-series classification.

Findings

Efficiently learns compact STL formulas using gradient-based tools.

Demonstrates improved interpretability and computational efficiency.

Validates approach on driving and naval surveillance case studies.

Abstract

Machine learning techniques using neural networks have achieved promising success for time-series data classification. However, the models that they produce are challenging to verify and interpret. In this paper, we propose an explainable neural-symbolic framework for the classification of time-series behaviors. In particular, we use an expressive formal language, namely Signal Temporal Logic (STL), to constrain the search of the computation graph for a neural network. We design a novel time function and sparse softmax function to improve the soundness and precision of the neural-STL framework. As a result, we can efficiently learn a compact STL formula for the classification of time-series data through off-the-shelf gradient-based tools. We demonstrate the computational efficiency, compactness, and interpretability of the proposed method through driving scenarios and naval surveillance case studies, compared with state-of-the-art baselines.