Shapelet Bottleneck Models for Explainable Time Series Classification

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Solution Overview

Problem

Deep learning models for time-series classification lack interpretability, making it difficult for experts to trust and understand the classification results, particularly in critical applications like healthcare where safety and reliability are essential.

Innovation Solution

The use of a shapelet concept bottleneck model (SCBM) with additional classification loss and regularization to determine the likelihood of shapelet occurrence, generating explainable time series classifications through a hybrid model combining shapelet concept bottleneck model (SBM) with a deep neural network (DNN) using a mixture-of-experts approach.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If deep learning models are used for time-series classification, then classification performance is improved, but interpretability deteriorates

Engineering Contradiction:
Improveclassification performanceVSAvoidinterpretability
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent segments the time series data into shapelet patterns and extracts meaningful temporal motifs from the data. By breaking down the complex time series into recognizable patterns (shapelets), the model maintains high classification performance while providing interpretable explanations about which patterns were detected and why they are significant for the classification decision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces shapelet patterns as intermediary representations between the raw time series data and the classification decision. These shapelets act as mediators that capture temporal dependencies and relationships, enabling the model to achieve state-of-the-art performance while maintaining interpretability through the extracted patterns.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of information

If shapelet concept bottleneck model is trained with additional classification loss and regularization, then explainability is improved, but training complexity increases

Engineering Contradiction:
ImproveexplainabilityVSAvoidtraining complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The patent merges the shapelet concept bottleneck model with a deep neural network in a hybrid architecture. The SCBM handles the interpretability aspect by extracting and explaining shapelet patterns, while the DNN handles the classification performance. This combination allows the system to achieve both explainability and high performance without excessive training complexity, as each component focuses on specific aspects of the problem.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs regularization techniques and additional classification loss functions that modify the training parameters and objective function. By adjusting these parameters and adding constraints, the model learns to produce both accurate classifications and interpretable explanations, balancing the trade-off between performance and explainability through parameter optimization.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS20250371323A1Explainable time series classification using shapelets
Publication Date: 2025.12.04 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • US20250371323A1 patent drawing
  • US20250371323A1 patent drawing
  • US20250371323A1 patent drawing

AI summary

Multivariate time series sample data is received. A shapelet concept bottleneck model (SCBM) is used to determine a likelihood that a shapelet occurs by calculating an mth dimension of a time series data point of the multivariate time series sample data and an mth dimension of univariate shapelet with length, where the shapelet concept bottleneck model is a linear layer over the likelihood of the shapelet occurring. The shapelet concept bottleneck model is trained with an additional classification loss with shapelet concept bottleneck model regularizations. The explainable time series classifications are generated based on the trained shapelet concept bottleneck model.