CEDAR: Automata as Verifiable Interfaces for Language-Guided Embodied Action

Lekai Chen, Alvaro Velasquez, Ashutosh Trivedi


Abstract
Natural-language tasking of embodied agents is rarely just goal specification: users also impose constraints that must persist while the world changes. Code-generating LLM agents can produce plausible behaviors for such instructions, but their free-form programs provide no stable object to verify, compose with new constraints, or repair from a failing trace. We present CEDAR, a counterexample-guided framework that grounds instructions as regular languages over environment event traces. CEDAR uses a language model for semantic judgments and execution traces for correction, then represents both skills and specifications as deterministic finite automata. This turns constraints into executable finite-state objects: a learned skill can be intersected with a learned sleep at night or stay in this biome specification, yielding a controller that enforces the learned constraint by construction rather than by repeated prompting. In Minecraft, with the same simulator/API observations available to a program-generating baseline, CEDAR maintains temporal and spatial constraints that the baseline fails to preserve and amortizes reuse of learned skills, reducing cumulative LLM queries. These results suggest that regular languages offer a practical verification layer between natural-language instructions and embodied-agent policies.
Anthology ID:
2026.findings-emnlp.652
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
13694–13710
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.652/
DOI:
10.18653/2026.findings-emnlp.652
Bibkey:
Cite (ACL):
Lekai Chen, Alvaro Velasquez, and Ashutosh Trivedi. 2026. CEDAR: Automata as Verifiable Interfaces for Language-Guided Embodied Action. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 13694–13710, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
CEDAR: Automata as Verifiable Interfaces for Language-Guided Embodied Action (Chen et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.652.pdf