arXiv AI

Multi-Step Knowledge Interaction Analysis via Rank-2 Subspace Disentanglement

The paper introduces a rank‑2 projection subspace to disentangle parametric knowledge (PK) and context knowledge (CK) in natural language explanations (NLEs) generated by large language models. Unlike prior work that used a rank‑1 subspace and focused on single‑step generation, this study performs a multi‑step analysis across longer NLE sequences, revealing richer interactions such as complementary or supportive knowledge. Experiments on four QA datasets and three open‑weight LLMs show that the rank‑2 subspace better captures diverse PK–CK dynamics, with hallucinated generations aligning strongly with PK and context‑faithful generations balancing PK and CK alignment.

arXiv Computation and Language
1d ago

Beyond Accuracy: What Language-Subspace Interventions Capture, Remove, and Improve

The paper investigates language‑subspace interventions designed to enhance multilingual reasoning by removing language‑related components from mid‑layer activations. Using MATH and MGSM datasets on four open‑weight LLMs, the authors examine whether these subspaces capture translation variation, whether projecting them out eliminates language information, and whether they improve accuracy without harming response language. Results show that the subspaces capture substantial translation variation but do not fully remove language signals, and that interventions can boost accuracy at the cost of language fidelity, highlighting the need to evaluate more than just accuracy.

By Shaanil Punglia, Dadhichi Telwadkar, Vaibhav Rathore, Siddharth Sureka, Neha Bhargava
arXiv Computation and Language
1d ago

ROSE: Risk-Aware Orthogonal Subspace Navigation for Lifelong Knowledge Editing in Multimodal Large Language Models

ROSE is a Risk‑Aware Orthogonal Subspace Navigation framework designed for lifelong knowledge editing in multimodal large language models. It limits parameter updates to the orthogonal complement of previously edited subspaces and uses a dynamic risk mask to protect critical factual parameters, thereby reducing catastrophic forgetting. During inference, ROSE applies prototype‑anchored semantic gating and perturbation‑driven subspace fusion to activate edited knowledge precisely for relevant queries while minimizing interference on unrelated inputs.

By Lingyun Song, Ziyao Chen, Kang Pan, Xiaolin Han, Yifei Zhang, Xiaoqi Wang, Yudai Pan, Xuequn Shang
arXiv AI
Sep 10

A*-Thought-V2: Efficient Latent Reasoning via Geometric Dynamics of LLM

A*-Thought-V2 is a framework that models Chain-of-Thought reasoning as a geometric trajectory in a 3D PCA space, using explicit-implicit latent tokens to compress steps that deviate from the main question-to-solution direction. The method measures alignment angles to decide which steps remain text and which become latent, and introduces stepwise embedding forcing and label forcing to train the architecture. Experiments on Qwen models show up to 2.6% accuracy gains, halved response length, and significant reductions in computation and training time.

By Xiaoang Xu, Siyuan Liu, Shuo Wang, Junlan Feng, Fanyu Meng, Zhu Zhang, Jixun Wang, Xiaorong Wang, Zihan Zhou, Xin Li, Chaojun Xiao, Yiming Zhang, Huijia Wu, Liuyu Xiang, Peipei Li, Zhaofeng He
arXiv AI
Aug 28

Grounded Token Initialization for New Vocabulary in LMs for Generative Recommendation

The paper examines how new vocabulary tokens are added to language models for generative recommendation tasks. It shows that the common practice of initializing these tokens as the mean of existing embeddings collapses them into a degenerate subspace, hindering fine‑tuning. The authors propose Grounded Token Initialization (GTI), which places new tokens at semantically meaningful positions in the pretrained embedding space using linguistic supervision, and demonstrate that GTI outperforms mean initialization and other adaptation methods across several benchmarks.

By Daiwei Chen, Zhoutong Fu, Chengming Jiang, Haichao Zhang, Ran Zhou, Tan Wang, Chunnan Yao, Guoyao Li, Rui Cai, Yihan Cao, Ruijie Jiang, Fedor Borisyuk, Jianqiang Shen, Jingwei Wu, Ramya Korlakai Vinayak
arXiv Computation and Language
Oct 19

What LLMs Do in the Shadows: Reading Context Reliance from the Unembedding Dark Space

The paper introduces DarkLens, a lightweight method for detecting faithfulness hallucinations in large language models (LLMs). It estimates context reliance by projecting hidden states onto the dark space—directions weakly aligned with the unembedding matrix—and uses the resulting Dark Matter Ratio (DMR) as a direct score of context utilization. Combined with a parametric knowledge score, DarkLens operates within a single forward pass and outperforms many baselines on QA and summarization benchmarks across several open‑weight LLMs.

By Alexandra Kuleshova, Andrey Volodichev, Daria Kotova, Alexey Zaytsev