arXiv Computation and Language
Sep 7

Compression Beyond the Uncompressed: A Two-Stage Training Recipe for Soft Context Compression in RAG

The paper introduces DEX-Comp, a two‑stage training method for soft context compression in Retrieval‑Augmented Generation (RAG). First, a pure distillation warm‑start trains the compression model on correct responses from an uncompressed RAG. Then, hard exploration uses reinforcement learning on queries where the uncompressed RAG fails, encouraging better computation patterns for compressed representations. Experiments on five open‑domain QA benchmarks show that DEX‑Comp compresses retrieved contexts 16×, speeds inference 4×–24×, and matches or surpasses the uncompressed RAG baseline across various retrieval depths.

By Shuyu Guo, Shuo Zhang, Zhaochun Ren
arXiv AI
Aug 19

DEPT: Document Embedding Preservation Tuning for Unified Query Expansion and Retrieval

The paper introduces DEPT, a method that trains a single decoder-only large language model to both expand queries and encode documents for retrieval. By preserving document embeddings close to their initial cached values while allowing gradients to flow through the generator, DEPT stabilizes retrieval targets and enables efficient index reuse and online hard‑negative mining. Experiments on the BEIR benchmark with Qwen3‑4B‑Instruct‑2507 and LLaMA‑3.2‑3B‑Instruct show that DEPT outperforms training‑free, independently trained, and staged unified baselines, with ablations confirming the benefits of preservation, whitening, end‑to‑end expansion training, and online negatives.

By Jingyuan Wang, Richong Zhang, Zhijie Nie, Mingxin Li, Yanzhao Zhang
arXiv Computation and Language
2d ago

Adamas: Hadamard Sparse Attention for Efficient Long-Context Inference

Adamas is a token‑level sparse attention mechanism that uses the Hadamard transform, bucketization, and 2‑bit compression to create compact representations, followed by lightweight distance‑based top‑k selection for efficient long‑context inference. It achieves near‑lossless performance on Llama‑3.1‑8B‑Instruct and delivers up to 6.5× speedup in self‑attention and 1.7× in end‑to‑end decoding at a 32K context length. Adamas also matches full attention performance on challenging long‑form reasoning benchmarks such as AIME 2024 and 2025.

By Siyuan Yan, Guo-Qing Jiang, Yuchen Zhang, Xiaoxing Ma, Ran Zhu, Chun Cao, Jingwei Xu