Checking Actions to Audit Explicit Price Agreements
Kevin Yamada · Team Kevin Yamada (solo)
Submitted to AI Collusion Research Sprint. Sprint projects are early-stage work by participants, not Apart Research publications.
An AI monitor must distinguish an agreement that was implemented from a proposal, a canceled deal, or coincidentally matching actions. I evaluate whether extracting evidence and checking it with deterministic code improves this distinction in scripted pricing records involving two sellers. Two studies compare direct model judgment, agreement extraction with trusted action logs, and extraction of both agreements and actions followed by verification. Study 1 reuses 16 wording families; Study 2 introduces 12 new families with several changes to an agreement. Across 28,224 model calls, I test Qwen2.5 7B and 32B and Mistral 7B on JSON, table and prose records under clean, misleading and neutral notes. On the main comparison on prose records without misleading notes, joint extraction improves balanced accuracy from 68.4% to 78.1% for Qwen 7B, 99.0% to 100% for Qwen 32B in Study 1, and 65.0% to 88.0% for Mistral 7B and 93.8% to 100% for Qwen 32B in Study 2. However, smaller models often violate the required output schema, especially with JSON inputs. All 1,640 invalid outputs remain failures. The results support evidence extraction plus verification for this narrow task, while exposing a reliability problem that depends on the input and output format. They do not establish detection of spontaneous collusion or robustness to compromised monitors.
Reviews
The project examines whether extracting evidence and verifying it with code can improve the detection of explicit price agreements between scripted AI agents. The team tested this method across two studies using different models, finding that joint extraction improved balanced accuracy in most cases, especially for prose records. However, smaller models struggled with JSON inputs, often failing to meet required output formats.
The main weakness is the limited scope and generalizability of the findings. While the results are promising within the controlled environment, they don't establish robustness against real-world strategic communication or spontaneous collusion. The reliance on scripted records and a single misleading note limits the practical applicability of these findings. Additionally, the lack of independent validation for the generated conversations introduces uncertainty about their realism.
To improve this work, the team should test the method with independently written cases and enforce output formats more strictly to better understand its reliability. Future experiments could also include real agent interactions and alternate messages and actions over time to assess the method's robustness under varied conditions. This project lays a foundation for further research into AI collusion detection but needs broader validation.
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Cite this project
@misc{yamada2026checking,
title = {{Checking Actions to Audit Explicit Price Agreements}},
author = {Kevin Yamada},
year = {2026},
month = oct,
note = {Submitted to AI Collusion Research Sprint, an Apart Research Sprint},
howpublished = {\url{https://apartresearch.com/sprints/projects/checking-actions-to-audit-explicit-price-agreements-3u7p}},
url = {https://apartresearch.com/sprints/projects/checking-actions-to-audit-explicit-price-agreements-3u7p}
}More from AI Collusion Research Sprint
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