Jiang, Pengcheng
RAS: Retrieval-And-Structuring for Knowledge-Intensive LLM Generation
Jiang, Pengcheng, Cao, Lang, Zhu, Ruike, Jiang, Minhao, Zhang, Yunyi, Sun, Jimeng, Han, Jiawei
Retrieval-augmented language models often struggle with knowledge-intensive tasks due to inefficient retrieval, unstructured knowledge integration, and single-pass architectures. We present Retrieval-And-Structuring (RAS), a novel framework that dynamically constructs and reasons over query-specific knowledge graphs through iterative retrieval and structuring. RAS introduces four key technical innovations: (1) a themescoped retrieval mechanism that efficiently narrows the search space while maintaining retrieval quality, (2) an action planning module that determines knowledge needs and generates focused sub-queries, (3) a dynamic knowledge structuring approach that converts retrieved text into an evolving knowledge graph, and (4) a graph-augmented answering component that leverages the accumulated structured information. Our framework achieves state-of-the-art performance, surpassing leading baselines by 6.4% with open-source language models and 7.0% with proprietary models on seven knowledge-intensive generation datasets across all evaluation metrics. Detailed ablation studies verify the contribution of each technical component to the overall system performance.
Taxonomy-guided Semantic Indexing for Academic Paper Search
Kang, SeongKu, Zhang, Yunyi, Jiang, Pengcheng, Lee, Dongha, Han, Jiawei, Yu, Hwanjo
Academic paper search is an essential task for efficient literature discovery and scientific advancement. While dense retrieval has advanced various ad-hoc searches, it often struggles to match the underlying academic concepts between queries and documents, which is critical for paper search. To enable effective academic concept matching for paper search, we propose Taxonomy-guided Semantic Indexing (TaxoIndex) framework. TaxoIndex extracts key concepts from papers and organizes them as a semantic index guided by an academic taxonomy, and then leverages this index as foundational knowledge to identify academic concepts and link queries and documents. As a plug-and-play framework, TaxoIndex can be flexibly employed to enhance existing dense retrievers. Extensive experiments show that TaxoIndex brings significant improvements, even with highly limited training data, and greatly enhances interpretability.
Reasoning-Enhanced Healthcare Predictions with Knowledge Graph Community Retrieval
Jiang, Pengcheng, Xiao, Cao, Jiang, Minhao, Bhatia, Parminder, Kass-Hout, Taha, Sun, Jimeng, Han, Jiawei
Large language models (LLMs) have demonstrated significant potential in clinical decision support. Yet LLMs still suffer from hallucinations and lack fine-grained contextual medical knowledge, limiting their high-stake healthcare applications such as clinical diagnosis. Traditional retrieval-augmented generation (RAG) methods attempt to address these limitations but frequently retrieve sparse or irrelevant information, undermining prediction accuracy. We introduce KARE, a novel framework that integrates knowledge graph (KG) community-level retrieval with LLM reasoning to enhance healthcare predictions. KARE constructs a comprehensive multi-source KG by integrating biomedical databases, clinical literature, and LLM-generated insights, and organizes it using hierarchical graph community detection and summarization for precise and contextually relevant information retrieval. Our key innovations include: (1) a dense medical knowledge structuring approach enabling accurate retrieval of relevant information; (2) a dynamic knowledge retrieval mechanism that enriches patient contexts with focused, multi-faceted medical insights; and (3) a reasoning-enhanced prediction framework that leverages these enriched contexts to produce both accurate and interpretable clinical predictions. Extensive experiments demonstrate that KARE outperforms leading models by up to 10.8-15.0% on MIMIC-III and 12.6-12.7% on MIMIC-IV for mortality and readmission predictions. In addition to its impressive prediction accuracy, our framework leverages the reasoning capabilities of LLMs, enhancing the trustworthiness of clinical predictions.
KG-FIT: Knowledge Graph Fine-Tuning Upon Open-World Knowledge
Jiang, Pengcheng, Cao, Lang, Xiao, Cao, Bhatia, Parminder, Sun, Jimeng, Han, Jiawei
Knowledge Graph Embedding (KGE) techniques are crucial in learning compact representations of entities and relations within a knowledge graph, facilitating efficient reasoning and knowledge discovery. While existing methods typically focus either on training KGE models solely based on graph structure or fine-tuning pre-trained language models with classification data in KG, KG-FIT leverages LLM-guided refinement to construct a semantically coherent hierarchical structure of entity clusters. By incorporating this hierarchical knowledge along with textual information during the fine-tuning process, KG-FIT effectively captures both global semantics from the LLM and local semantics from the KG. Extensive experiments on the benchmark datasets FB15K-237, YAGO3-10, and PrimeKG demonstrate the superiority of KG-FIT over state-of-the-art pre-trained language model-based methods, achieving improvements of 14.4%, 13.5%, and 11.9% in the Hits@10 metric for the link prediction task, respectively. Furthermore, KG-FIT yields substantial performance gains of 12.6%, 6.7%, and 17.7% compared to the structure-based base models upon which it is built. These results highlight the effectiveness of KG-FIT in incorporating open-world knowledge from LLMs to significantly enhance the expressiveness and informativeness of KG embeddings.
TriSum: Learning Summarization Ability from Large Language Models with Structured Rationale
Jiang, Pengcheng, Xiao, Cao, Wang, Zifeng, Bhatia, Parminder, Sun, Jimeng, Han, Jiawei
The advent of large language models (LLMs) has significantly advanced natural language processing tasks like text summarization. However, their large size and computational demands, coupled with privacy concerns in data transmission, limit their use in resource-constrained and privacy-centric settings. To overcome this, we introduce TriSum, a framework for distilling LLMs' text summarization abilities into a compact, local model. Initially, LLMs extract a set of aspect-triple rationales and summaries, which are refined using a dual-scoring method for quality. Next, a smaller local model is trained with these tasks, employing a curriculum learning strategy that evolves from simple to complex tasks. Our method enhances local model performance on various benchmarks (CNN/DailyMail, XSum, and ClinicalTrial), outperforming baselines by 4.5%, 8.5%, and 7.4%, respectively. It also improves interpretability by providing insights into the summarization rationale.
GenRES: Rethinking Evaluation for Generative Relation Extraction in the Era of Large Language Models
Jiang, Pengcheng, Lin, Jiacheng, Wang, Zifeng, Sun, Jimeng, Han, Jiawei
The field of relation extraction (RE) is experiencing a notable shift towards generative relation extraction (GRE), leveraging the capabilities of large language models (LLMs). However, we discovered that traditional relation extraction (RE) metrics like precision and recall fall short in evaluating GRE methods. This shortfall arises because these metrics rely on exact matching with human-annotated reference relations, while GRE methods often produce diverse and semantically accurate relations that differ from the references. To fill this gap, we introduce GenRES for a multi-dimensional assessment in terms of the topic similarity, uniqueness, granularity, factualness, and completeness of the GRE results. With GenRES, we empirically identified that (1) precision/recall fails to justify the performance of GRE methods; (2) human-annotated referential relations can be incomplete; (3) prompting LLMs with a fixed set of relations or entities can cause hallucinations. Next, we conducted a human evaluation of GRE methods that shows GenRES is consistent with human preferences for RE quality. Last, we made a comprehensive evaluation of fourteen leading LLMs using GenRES across document, bag, and sentence level RE datasets, respectively, to set the benchmark for future research in GRE
Bi-level Contrastive Learning for Knowledge-Enhanced Molecule Representations
Jiang, Pengcheng, Xiao, Cao, Fu, Tianfan, Sun, Jimeng
Molecule representation learning is crucial for various downstream applications, such as understanding and predicting molecular properties and side effects. In this paper, we propose a novel method called GODE, which takes into account the two-level structure of individual molecules. We recognize that molecules have an intrinsic graph structure as well as being a node in a larger molecule knowledge graph. GODE integrates graph representations of individual molecules with multidomain biochemical data from knowledge graphs. By pre-training two graph neural networks (GNNs) on different graph structures, combined with contrastive learning, GODE fuses molecular structures with their corresponding knowledge graph substructures. This fusion results in a more robust and informative representation, which enhances molecular property prediction by harnessing both chemical and biological information. When fine-tuned across 11 chemical property tasks, our model outperforms existing benchmarks, registering an average ROC-AUC uplift of 13.8% for classification tasks and an average RMSE/MAE enhancement of 35.1% for regression tasks. Impressively, it surpasses the current leading model in molecule property predictions with average advancements of 2.1% in classification and 6.4% in regression tasks.
GraphCare: Enhancing Healthcare Predictions with Personalized Knowledge Graphs
Jiang, Pengcheng, Xiao, Cao, Cross, Adam, Sun, Jimeng
Clinical predictive models often rely on patients' electronic health records (EHR), but integrating medical knowledge to enhance predictions and decision-making is challenging. This is because personalized predictions require personalized knowledge graphs (KGs), which are difficult to generate from patient EHR data. Our method extracts knowledge from large language models (LLMs) and external biomedical KGs to build patient-specific KGs, which are then used to train our proposed Bi-attention AugmenTed (BAT) graph neural network (GNN) for healthcare predictions. On MIMIC-III, it boosts AUROC by 17.6% and 6.6% for mortality and readmission, and F1-score by 7.9% and 10.8% for LOS and drug recommendation, respectively. To improve predictive performance and integrate expert knowledge with data insights, clinical knowledge graphs (KGs) were adopted to complement EHR modeling (Chen et al., 2019; Choi et al., 2020; Rotmensch et al., 2017). These KGs represent medical concepts (e.g., diagnoses, procedures, drugs) and their relationships, enabling effective learning of patterns and dependencies. However, existing approaches mainly focus on simple hierarchical relations (Choi et al., 2017; 2018; 2020) rather than leveraging comprehensive relationships among biomedical entities despite incorporating valuable contextual information from established biomedical knowledge bases (e.g., UMLS (Bodenreider, 2004)) could enhance predictions. Moreover, large language models (LLMs) such as GPT (Brown et al., 2020; Chowdhery et al., 2022; Luo et al., 2022; OpenAI, 2023) pre-trained on web-scale biomedical literature could serve as alternative resources for extracting clinical knowledge given their remarkable reasoning abilities on open-world data. There is a substantial body of existing research demonstrating their potential use as knowledge bases (Lv et al., 2022; Petroni et al., 2019; AlKhamissi et al., 2022). To fill the gap in personalized medical KGs, we propose to leverage the exceptional reasoning abilities of LLMs to extract and integrate personalized KG from open-world data. Below: For each patient, we compose a patient-specific graph by combining the concept-specific KGs associated with them and make the graph temporal with sequential data across patient's visits ( 3.2). To utilize the patient graph for predictions, we employ a bi-attention augmented graph neural network (GNN) model, which highlights essential visits and nodes with attention weights ( 3.3). As shown in Figure 1, our patient KG generation module first takes medical concepts as input and generates concept-specific KGs by prompting LLMs or retrieving subgraphs from existing graphs.
Text-Augmented Open Knowledge Graph Completion via Pre-Trained Language Models
Jiang, Pengcheng, Agarwal, Shivam, Jin, Bowen, Wang, Xuan, Sun, Jimeng, Han, Jiawei
The mission of open knowledge graph (KG) completion is to draw new findings from known facts. Existing works that augment KG completion require either (1) factual triples to enlarge the graph reasoning space or (2) manually designed prompts to extract knowledge from a pre-trained language model (PLM), exhibiting limited performance and requiring expensive efforts from experts. To this end, we propose TAGREAL that automatically generates quality query prompts and retrieves support information from large text corpora to probe knowledge from PLM for KG completion. The results show that TAGREAL achieves state-of-the-art performance on two benchmark datasets. We find that TAGREAL has superb performance even with limited training data, outperforming existing embedding-based, graph-based, and PLM-based methods.