Papers by Ignacio Sastre
Concept Tokens: Learning Behavioral Embeddings Through Concept Definitions (2026.findings-acl)
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| Challenge: | Concept Tokens is a lightweight method that adds a special token to a pretrained LLM . we find that negating the hallucination token reduces hallucines and lowers precision . |
| Approach: | They propose a lightweight method that adds a new special token to a pretrained LLM and learns only its embedding from multiple natural language definitions of a target concept. |
| Outcome: | The proposed method can learn only its embedding from multiple definitions of a target concept . the study shows that it can improve hallucinations and recasting in closed-book questions . |