Bi-Encoder and Cross-Encoder Retrieval Fine-Tuning for Domain Accuracy

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Solution Overview

Problem

Large language models struggle to provide domain-specific and up-to-date information due to their general-purpose training, limiting their effectiveness in specialized domains like manufacturing, finance, and healthcare, and the quality of retrieved chunks significantly affects the performance of retrieve-then-read pipelines.

Innovation Solution

Fine-tuning bi-encoding and cross-encoding models using synthetic training data generated by large language models to identify and rank relevant chunks of information, enhancing the retriever model's ability to provide high-quality inputs to generative models.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If large language models are trained on general-purpose data, then they can handle diverse tasks, but they cannot provide domain-specific and up-to-date information

Engineering Contradiction:
Improvetask diversityVSAvoiddomain-specific accuracy
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system segments the retrieval process into two distinct models: bi-encoding for initial retrieval and cross-encoding for re-ranking. This segmentation allows each model to be optimized for its specific function, with the cross-encoding model specializing in domain-specific accuracy while the bi-encoding model handles diverse query types efficiently.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system performs preliminary retrieval using bi-encoding to identify candidate chunks before applying the more computationally intensive cross-encoding re-ranking. This preliminary action filters the search space, allowing the cross-encoding model to focus computational resources on refining the most promising candidates for domain-specific accuracy.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If cross-encoding model is used for re-ranking, then retrieval accuracy improves, but computational cost increases

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

Solution Approach 1:

The system applies cross-encoding re-ranking only to the top-k candidate chunks identified by bi-encoding, rather than re-ranking all retrieved chunks. This partial action maintains high retrieval accuracy for the most important results while significantly reducing the computational cost compared to applying cross-encoding to the entire corpus.

Inventive Principle:
Principle #16Partial or excessive action

Solution Approach 2:

The bi-encoding model serves as an intermediary that pre-filters the corpus to identify candidate chunks worthy of cross-encoding re-ranking. This intermediary step bridges the gap between efficient initial retrieval and accurate final ranking, reducing the overall computational burden while maintaining high retrieval accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If more training data is used to fine-tune retriever models, then domain-specific performance improves, but data generation time increases

Engineering Contradiction:
Improvedomain-specific performanceVSAvoiddata generation time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system generates synthetic training data in advance using domain-specific guidelines and expert knowledge, storing it for future use in fine-tuning the cross-encoding model. This preliminary data generation eliminates the need for time-consuming manual annotation during deployment while ensuring high domain-specific performance through carefully crafted training examples.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses automatically generated synthetic data with simulated relevance labels to fine-tune the retriever models, eliminating the need for manual expert annotation. This self-service approach to data generation significantly reduces the time and resources required while maintaining domain-specific performance through algorithmic generation of realistic training scenarios.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS20260050842A1Data generation and retraining techniques for fine-tuning of bi-encoding and cross-encoding models for efficient data retrieval
Publication Date: 2026.02.19 GOLDMAN SACHS & CO LLC
  • US20260050842A1 patent drawing
  • US20260050842A1 patent drawing
  • US20260050842A1 patent drawing

AI summary

A method includes obtaining a raw text corpus and a set of seed queries. The method also includes training a retrieval pipeline having a bi-encoding model and a cross-encoding model using the raw text corpus and the set of seed queries. The method further includes outputting a trained bi-encoding model and a trained cross-encoding model. Training the retrieval pipeline includes (i) training the bi-encoding model to perform initial embedding-based retrieval of segments from the raw text corpus and (ii) training the cross-encoding model to perform re-ranking or refinement of the retrieved segments.