Differentially Private Parameter Retraining for ML Systems

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Solution Overview

Problem

Machine learning systems tend to 'remember' information from non-public training data, potentially revealing sensitive information during inference, and existing differentially private training methods face challenges in efficiently adjusting parameters within a limited privacy budget.

Innovation Solution

The method involves gradient-based retraining of a machine learning system by adjusting a small number of parameters using non-public training data, with the addition of further parameters through additional layers or weight matrix modifications, and employing a differentially private backpropagation method to minimize information leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a machine learning system is trained with non-public training data to improve performance on a target task, then the system's performance and adaptability improve, but the risk of sensitive information leakage increases

Engineering Contradiction:
Improveperformance on target taskVSAvoidinformation leakage risk
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the parameter adjustment process into two distinct phases: pre-training with public data to establish baseline performance, and retraining with non-public data to adapt to specific target tasks. This segmentation allows the system to benefit from non-public data while limiting exposure by restricting which parameters are adjusted during retraining.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by selectively adjusting only specific parameters (those added during retraining) while keeping the majority of pre-trained parameters frozen. This localized parameter adjustment minimizes the information that can be extracted from non-public training data while maintaining task-specific performance improvements.

Inventive Principle:
Principle #3Local quality

2Adaptability or versatility

If more parameters are adjusted during retraining with non-public data, then the system's adaptability to the target task improves, but the training time and computational resources increase

Engineering Contradiction:
Improveadaptability to target taskVSAvoidtraining time
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent extracts and isolates only the necessary parameters for target task adaptation, adding them separately from the pre-trained parameters. During retraining, only these extracted parameters are adjusted, significantly reducing training time and computational overhead while maintaining adaptability to the target task.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial action by adjusting only a subset of parameters during retraining rather than all parameters. This partial adjustment is sufficient to achieve target task adaptability while avoiding the excessive computational cost of full parameter retraining.

Inventive Principle:
Principle #16Partial or excessive action

3Loss of information

If a larger number of parameters are adjusted in retraining, then the machine learning system can better utilize non-public information, but the probability of overfitting and poor generalization increases

Engineering Contradiction:
Improveutilization of non-public informationVSAvoidgeneralization performance
Core Design Contradiction:
Loss of informationVSReliability

Solution Approach 1:

The patent performs preliminary action by pre-training the system with public data before introducing non-public data. This establishes a robust baseline that prevents overfitting to non-public information, as the majority of parameters are already optimized from diverse public data sources.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

By limiting parameter adjustments to only those added during retraining, the patent ensures that non-public information is incorporated in a controlled, localized manner rather than comprehensively across the entire system, reducing overfitting risk while maintaining information utilization.

Inventive Principle:
Principle #3Local quality

Data Source

PatentUS20250037024A1Method and device for retraining a machine learning system
Publication Date: 2025.01.30 ROBERT BOSCH GMBH
  • US20250037024A1 patent drawing
  • US20250037024A1 patent drawing

AI summary

A method for gradient-based retraining of a machine learning system with non-public training data with regard to a target task. The method includes: adding further parameters to the pre-trained machine learning system, and adjusting the added further parameters with the non-public training data using a differentially private backpropagation method, wherein the added parameters are adjusted with regard to the target task.