Prompt Classifier Cascades for Imbalanced Text Classification

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Solution Overview

Problem

Existing multi-classification models, including prompt-based learning classifiers, struggle with imbalanced datasets, leading to performance drops due to unequal data distribution across classes, especially in text classification tasks.

Innovation Solution

A method involving a multi-stage prompt-based learning classifier that organizes datasets based on class frequency, performs reverse multi-stage training, and forward multi-stage inference, leveraging a pre-trained Language Model (LM) to handle imbalanced datasets efficiently and reduce model bias.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a pre-trained Language Model is used for text classification, then classification accuracy is improved, but computational cost increases

Engineering Contradiction:
Improveclassification accuracyVSAvoidcomputational cost
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent segments the multi-class classification problem into multiple binary classification stages. Instead of using a single pre-trained LM for all classes, the system divides the task into sequential binary decisions, allowing lighter models to handle simpler discrimination tasks while maintaining overall accuracy.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial action by using simplified classification approaches for certain stages rather than applying the full pre-trained LM capacity to every classification decision. This reduces computational overhead while maintaining necessary accuracy through selective application of model complexity.

Inventive Principle:
Principle #16Partial or excessive action

2Reliability

If ensemble machine learning techniques are used, then robustness in imbalanced class scenario is improved, but device complexity increases

Engineering Contradiction:
Improverobustness in imbalanced class scenarioVSAvoidmodel complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the complex ensemble problem into simpler sequential binary classification stages. Each stage handles a specific discrimination task, reducing the overall complexity while maintaining robustness through the staged approach to handling imbalanced classes.

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If prompt-based learning classifiers are used, then text classification capability is improved, but performance drops on imbalanced datasets

Engineering Contradiction:
Improvetext classification capabilityVSAvoidperformance on imbalanced datasets
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the multi-class prompt-based classification into binary classification stages. This segmentation allows each stage to focus on distinguishing between two classes, improving performance on imbalanced datasets by avoiding the pitfalls of direct multi-class prompt-based approaches.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent inverts the traditional approach by using binary classification stages rather than direct multi-class prompt-based learning. This inversion allows the system to handle imbalanced data more effectively by breaking down the complex multi-class problem into manageable binary decisions.

Inventive Principle:
Principle #13The other way round (Inversion)

Data Source

PatentUS20260030506A1Prompt-classifier method for multiclass text classification in imbalanced data
Publication Date: 2026.01.29 DELL PROD LP
  • US20260030506A1 patent drawing
  • US20260030506A1 patent drawing
  • US20260030506A1 patent drawing

AI summary

One example method includes organizing, using prompt-classifiers (PC), an imbalanced dataset into ‘n’ different classes, and the organizing comprises performing a frequency analysis that identifies a respective number of samples in each of the ‘n’ different classes, and the organizing further comprises structuring, based on the frequency analysis, the imbalanced dataset using a cascaded one-versus-all approach to identify a target class and two remaining classes. Next, the method includes performing a reverse multi-stage prompt-classifier training process that comprises training the prompt-classifiers using the target classes and the two remaining classes, and the training is performed in reverse of an order in which the prompt-classifiers were used to organize the imbalanced dataset. Finally, the method includes performing an inferencing process using one or more of the prompt-classifiers, and the inferencing process continues until a then-current one of the prompt-classifiers correctly identifies the target class.