Noise-Robust Semi-Supervised Learning via GAN Transition Matrix

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Solution Overview

Problem

Traditional semi-supervised learning methods, such as GANs, are not designed to handle noisy class labels effectively, leading to performance degradation when labels are inaccurate, which is common due to human error or subjective classification tasks in areas like image analysis and microarray gene expression classification.

Innovation Solution

A noise-robust semi-supervised learning method based on generative adversarial networks (GANs) is introduced, incorporating a denoising layer with discriminator and generator loss functions that include a pull-away term and feature match term to enhance performance in the presence of noisy labels, specifically addressing asymmetric noise by widening the density gap.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional semi-supervised GAN is used for classification, then the system can handle unlabeled data, but performance degrades dramatically when class labels contain noise

Engineering Contradiction:
Improveclassification performanceVSAvoidlabel accuracy
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent transforms the harmful effect of noisy labels into a beneficial training signal by generating fake noisy samples that mimic real noise patterns. These synthetic noisy samples are then used to train the discriminator to be robust against label noise, effectively converting the problem of noise sensitivity into a strength of noise tolerance.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent performs preliminary noise characterization by analyzing the transition matrix of noisy labels before main training. This preliminary analysis allows the system to pre-generate fake noisy samples with matching noise characteristics, preparing the training data in advance to match the expected noise patterns in the real dataset.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If more classified data is collected to improve training, then classification accuracy improves, but the cost of manual labeling increases significantly

Engineering Contradiction:
Improveclassification accuracyVSAvoidlabeling time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent creates synthetic copies of labeled data by generating fake samples that mimic the statistical properties of real noisy labeled data. These synthetic copies are generated using the transition matrix derived from real noisy labels, allowing the model to learn from expanded training data without requiring additional manual labeling effort.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent transforms the training process by changing the parameters of the training data distribution. By using the transition matrix to generate fake noisy samples with specific noise characteristics, the system effectively changes the data distribution parameters to match real-world noisy conditions, improving robustness without collecting more real labeled data.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the density gap between classes is reduced for better classification, then classification boundaries become softer, but the system becomes more sensitive to label noise

Engineering Contradiction:
Improvenoise robustnessVSAvoidclassification boundary precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces asymmetric treatment of different data types in the training process. Real noisy labeled data and fake noisy generated data are handled differently by the discriminator, which is trained to distinguish between them while learning robust classification boundaries that are less sensitive to label noise.

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentUS11087215B1Machine learning classification system
Publication Date: 2021.08.10 SAS INSTITUTE INC
  • US11087215B1 patent drawing
  • US11087215B1 patent drawing
  • US11087215B1 patent drawing

AI summary

A computing device classifies unclassified observations. A first batch of noise observations is generated. (A) A first batch of unclassified observations is selected. (B) A first batch of classified observations is selected. (C) A discriminator neural network model trained to classify unclassified observations and noise observations is updated with observations that include the first batch of unclassified observations, the first batch of classified observations, and the first batch of noise observations. (D) A discriminator loss value is computed that includes an adversarial loss term computed using a predefined transition matrix. (E) A second batch of unclassified observations is selected. (F) A second batch of noise observations is generated. (G) A generator neural network model trained to generate a fake observation vector for the second batch of noise observations is updated with the second batch of unclassified observations and the second batch of noise observations. (H) (A) to (G) is repeated.