arXiv Machine Learning

Calibrated Fusion for Heterogeneous Graph-Vector Retrieval in Multi-Hop QA

arXiv Machine Learning
Sep 21

Predictable Failure in Multi-Hop Retrieval: Score-Distributional Confidence Scoring and Abstention

The paper shows that multi‑hop retrieval failures cluster in predictable subpopulations and formalizes this with two theoretical results: (1) confident‑failure reduction is possible only when retrieval features carry mutual information about success, and (2) no single ANN score feature dominates across all failure regimes. Building on these insights, the authors introduce RegimeAbstain, which computes a Retrieval Confidence Score (RCS) from up to nine query‑ANN structural features and uses it to calibrate an abstention policy. Across three benchmarks and two retrieval architectures, RCS achieves the best or co‑best AUC‑AC and significantly reduces the Confident‑Wrong‑Answer Rate, demonstrating its effectiveness and domain‑agnostic applicability.

By Andre Bacellar
arXiv Machine Learning
3d ago

Relative Kinetic Utility: Calibrating Cross-Layer Credit for Global Structured LLM Pruning

The paper introduces Global Relative Kinetic Utility (Global RKU), a label‑free method for calibrating cross‑layer credit in global structured pruning of large language models. Global RKU estimates channel importance via a final‑hidden‑state activation‑gradient signal and applies block‑relative normalization to remove block‑common scale while preserving within‑block ordering, enabling a single‑stage static pruning topology. Experiments on Qwen‑2.5‑7B show significant performance gains at various sparsity levels, and ablation studies confirm the effectiveness of the relative‑normalization step.

By Tianhao Qian, Guilin Qi, Jiayu Chen
arXiv Computation and Language
Aug 25

FCPRAG: Fusion-Controller Parametric Retrieval-Augmented Generation for Stable Multi-Passage LoRA Injection

FCPRAG introduces a fusion-controlled parametric retrieval‑augmented generation framework that uses a lightweight controller to predict per‑passage fusion scores and sample‑level calibration signals, such as a mixing gate and adaptive temperature. This approach mitigates the bottleneck of evidence‑level fusion when multiple passages are retrieved, enabling selective fusion under informative signals and conservative fusion under uncertainty. Experiments on HotpotQA, 2WikiMultiHopQA, PopQA, and ComplexWebQuestions demonstrate consistent F1 improvements over standard RAG and parametric RAG baselines, with gains up to 4.65% on 2WikiMultiHopQA and 7.55% on CWQ, while also reducing tuning cost and enhancing robustness to retrieval perturbations.

By Jinchang Zhu, Jindong Li, Yi Ding, Xiaojian Nie, Rong Fu, Shuangyong Song, Haowei He, Menglin Yang
arXiv AI
Sep 3

Hybrid Retrieval-Augmented Generation with Knowledge Graph Expansion, RRF Fusion, and Per-Chunk Grounded Evaluation for Enterprise Document Search

Hybrid Retrieval-Augmented Generation with Knowledge Graph Expansion, RRF Fusion, and Per-Chunk Grounded Evaluation for Enterprise Document Search describes DocuSearch, an offline multi‑agent system designed for telecom network operations. The system combines semantic vector search, BM25 full‑text search, and knowledge‑graph neighbor expansion, merges the results via Reciprocal Rank Fusion, and reranks with a cross‑encoder before pruning with Maximal Marginal Relevance. A per‑chunk evaluation loop ensures only grounded answers are returned, achieving Precision@10 of 0.69, Recall@10 of 0.79, and an 89.6% grounding rate—improvements of 15, 16, and 18.4 percentage points over a dense‑only baseline.

By Harish Saragadam, Sudhanshu Sharma, Meghana Pujari
arXiv Computation and Language
Aug 28

MoganColBERT-TR: A Late-Interaction Multi-Vector Retrieval Model for Turkish

MoganColBERT-TR is a Turkish multi‑vector retrieval model that projects token embeddings from 768 to 128 dimensions and uses MaxSim late interaction for scoring. It builds on the previously trained MoganBERT‑TR encoder, adapting it to the ColBERT objective with a single‑epoch distillation phase using cross‑encoder teacher scores. Evaluated on five Turkish BEIR datasets in a zero‑shot setting, it achieves an overall score of 37.36, outperforming larger models on most datasets.

By Furkan Yilmaz, Habibe Aleyna Tasdemir, Muhammed Faruk Gozay