arXiv AI

Encoding and Propagation of Grammatical Number in Large Language Models

The study uses sparse autoencoders (SAEs) to probe how the Pythia-70M language model encodes grammatical number. By identifying and manipulating SAE‑derived features such as "plural noun" and "generate a plural verb," the authors show that removing these features forces the model to produce singular verbs, and vice versa. Similar asymmetries were observed in larger models (Gemma‑2‑2b and Llama‑3.1‑8b), indicating a privative representation of number in English.

arXiv Computation and Language
Sep 25

Scoring Both Directions: LLMs realize the MRS they cannot reliably parse

The paper evaluates two large language models, Claude Sonnet 4.5 and Claude Opus 5, on the bidirectional English Resource Grammar (ERG) tasks of generating English from Minimal Recursion Semantics (MRS) and parsing English into MRS. In generation, Opus achieves 76.3 BLEU—surpassing a 72k‑pair trained system and matching a million‑pair system—while Sonnet scores 65.7 BLEU, rising to 69.6 when selecting from ACE’s candidates. In parsing, both models lag behind ACE, attaining only 57.2 and 65.5 F₁ respectively, with exact‑match on about 1 % of sentences, highlighting that high generation scores do not guarantee accurate semantic parsing.

By Soham Dan
arXiv Computation and Language
Oct 22

Why is AI-generated language so hard to understand?

The paper investigates why AI-generated text has become harder to understand, focusing on psycholinguistic features linked to human processing difficulty such as object relative clauses, long syntactic dependencies, and low-frequency n-grams. Using a new corpus of AI-generated text from diverse domains, the study finds that frontier and near-frontier language models employ these difficult features more frequently than paraphrases from round-trip translation and human writing, including more inanimate subjects with animate verbs, longer dependencies, stacked nouns, and reduced object relatives. The authors hypothesize that AI models prioritize information density for tasks like math, code, and reasoning, diverging from human communication goals, and demonstrate this by fine‑tuning a model with a length penalty, which reduces human‑like linguistic behavior.

By Thomas Hikaru Clark, Matias B. Martin, Kyle Mahowald
arXiv Computation and Language
Sep 18

Generalization through Lexical Abstraction in Transformer Models: The Case of Functional Words

The study investigates whether pretrained transformer models encode functional words—such as pronouns and adverbs—in a way that mirrors human usage. By comparing embeddings of nouns with those of their functional counterparts in both isolated and parallel sentences, the authors find that functional words occupy a central yet distinct position in embedding space and that parallel lexicalized and functional sentences reside in different subspaces. Experiments show that only a mixed training set of functional and lexicalized sentences reveals shared syntactic and semantic structure, whereas training on either type alone fails to capture this parallelism.

By Giuseppe Samo, Vivi Nastase, Paola Merlo
arXiv Computation and Language
Oct 27

Large Language Model probabilities cannot reliably distinguish between possible and impossible language

arXiv:2509.15114v2 Announce Type: replace Abstract: A controversial test for Large Language Models concerns the ability to discern possible from impossible language. While some evidence attests to th...

By Evelina Leivada, Raquel Montero, Paolo Morosi, Natalia Moskvina, Tamara Serrano, Nikoleta Pantelidou, Marcel Aguilar, Fritz Guenther
arXiv Computation and Language
Aug 31

Diverging Transformer Predictions for Human Sentence Processing: A Comprehensive Analysis of Agreement Attraction Effects

The study evaluates eleven autoregressive transformer models on English agreement attraction scenarios using a surprisal-based approach. Results show that while transformers match human reading times for prepositional phrase configurations, they perform poorly on object‑extracted relative clauses, with predictions diverging across models and failing to capture human interference patterns. The authors argue that current transformers cannot adequately model human morphosyntactic processing and call for more rigorous, comprehensive testing to avoid misleading conclusions from limited syntactic setups.

By Titus von der Malsburg, Sebastian Pad\'o
arXiv AI
Oct 1

Functional Subspace, where language models can use vector algebra to solve problems

The paper proposes that large language models (LLMs) encode high‑level concepts as linear directions within their activation space and that they can use subspaces and vector algebra to perform tasks. By analyzing functional modules and residual streams during in‑context learning (ICL), the authors find that LLMs can create evidence‑accumulating subspaces and solve ICL tasks through simple algebraic operations within those subspaces.

By Jung H. Lee, Sujith Vijayan
arXiv Computation and Language
Oct 19

From Parallels to Divergence: Language Models' Learning of Action Nominal Constructions

The paper examines how language models learn action nominal constructions (ANCs) across 96 synthetic target languages with varied grammatical features. Using GPT‑2‑small trained from scratch, the study evaluates models on minimal pairs covering 34 grammatical phenomena, revealing that models mirror typological patterns in basic clause configurations but diverge in complement systems and ANC strategies. The findings suggest that natural language distributions may arise from both general learning pressures and functional demands not fully captured by current model experiments.

By Iskar Deng, Shane Steinert-Threlkeld
arXiv Machine Learning
Oct 15

Sparse Autoencoders Are a Shared Coordinate System for Symbolic Matching

The paper introduces SAE‑IDF, a data‑driven approach that uses sparse autoencoders to encode symbols into interpretable sparse codes, re‑weights dimensions by rarity, and matches units across heterogeneous symbolic systems. On 12 tasks spanning six symbolic system types, SAE‑IDF outperforms dense LLM baselines (Gemma‑2‑9B and Llama‑3.1‑8B) by up to 45 points, consistently across layers and configurations. Each sparse dimension carries a human‑readable meaning, allowing matches to decompose into named concepts, thereby enabling a scalable, universal symbolic backbone.

By Xiaocong Yang, Xuanyu Meng, Yuji Zhang, Jiawei Han, ChengXiang Zhai