LLM Knowledge Retrieval With Hybrid Lexical-Semantic Ranking

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

The retrieval of relevant documents becomes difficult due to the vast number of documents and the temporal aspect of their relevance, especially in business contexts where information relevance varies over time, such as in customer support systems.

Innovation Solution

A system utilizing a large language model (LLM)-based embedding model to transform natural language queries into vector embeddings, employing a hybrid approach that leverages both lexical and semantic aspects to retrieve and rank knowledge resources from knowledge bases, incorporating advanced techniques like transformer-based models and hierarchical navigable small world indexing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional retrieval algorithms are used to search through large corpora, then the system can retrieve documents, but the accuracy and relevance of results deteriorate due to the vast number of documents and temporal variations in information relevance

Engineering Contradiction:
Improverelevance accuracyVSAvoidnumber of documents
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent introduces an LLM-based embedding model as an intermediary between the query and the document corpus. This model transforms both queries and documents into vector embeddings, enabling semantic similarity search that captures the meaning and temporal relevance of information. The embedding model acts as a mediator that filters and ranks documents based on semantic relevance rather than just keyword matching, thereby improving relevance accuracy in large corpora.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent transforms the retrieval problem by changing the parameter space from keyword-based text matching to vector-based semantic space. By converting documents and queries into high-dimensional vector representations, the system can measure relevance through distance metrics in the embedding space, which captures temporal and contextual nuances that traditional algorithms miss.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If traditional keyword-based search is used, then the system can handle simple queries, but it fails to capture semantic meaning and temporal relevance of information

Engineering Contradiction:
Improvesemantic understandingVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical keyword-matching algorithms with an LLM-based embedding system that captures semantic meaning. Instead of relying on exact word matches, the system uses neural network embeddings to understand the semantic relationships between queries and documents, enabling the system to handle nuanced business queries with temporal aspects.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The LLM-based embedding model serves multiple functions: it transforms text to vectors, captures semantic meaning, handles temporal relevance, and works across different domains and query types. This universal approach replaces multiple specialized algorithms, making the system more adaptable to various business contexts while managing complexity through a unified framework.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If all retrieved documents are processed and ranked using traditional methods, then the system can provide results, but network bandwidth and processing time are excessively consumed

Engineering Contradiction:
Improveretrieval efficiencyVSAvoidnetwork bandwidth
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent performs preliminary embedding of documents into vector space before retrieval. This pre-processing step allows the system to quickly compute similarity scores between query embeddings and document embeddings, filtering out irrelevant documents early in the process. By ranking documents based on embedding similarity before full text processing, the system reduces network bandwidth consumption and improves retrieval efficiency.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS20250355912A1Large language model (LLM)-based knowledge resource retriever and ranker
Publication Date: 2025.11.20 SAP SE
  • US20250355912A1 patent drawing
  • US20250355912A1 patent drawing
  • US20250355912A1 patent drawing

AI summary

Disclosed herein are a system, method, and computer program product embodiments for retrieving and ranking knowledge resources relevant to a query from knowledge base(s). For example, a query for resources from knowledge base(s) may be received. Based on the query, a first set of candidate resources are obtained from the knowledge base(s) having a lexical similarity to the query search terms, and a second set of candidate resources are obtained from the knowledge base(s) having a semantical similarity to the search terms. For each of the first and second sets of candidate resources, a confidence level indicating the relevance of the candidate resource to the query is determined. The sets of candidate resources are ranked based on at least the confidence levels to generate a ranked list of candidate resources. A query response comprising at least a subset of the ranked list candidate resources is provided to a GUI.