π€ AI Summary
Ambiguity in defining βopen-source foundation modelsβ and the absence of standardized openness criteria hinder effective AI governance. Method: We formulate a two-tiered game-theoretic model between generalist model creators and specialist fine-tuners to analyze how alternative open-model regulatory policies affect upstream release decisions and downstream fine-tuning effort. Contribution/Results: We propose a novel performance-threshold-based framework for defining open-source models and identify asymmetric incentive effects of regulatory penalties and openness thresholds on both stakeholders. Through formal modeling, incentive-compatibility analysis, and policy simulation, we quantify market responses under multiple openness standards and characterize an effective regulatory regime: moderate penalties combined with calibrated performance thresholds jointly promote innovation incentives and risk mitigation. Our work provides a practically implementable paradigm for defining open-source AI models and informs differentiated, evidence-based regulatory design.
π Abstract
Regulatory frameworks, such as the EU AI Act, encourage openness of general-purpose AI models by offering legal exemptions for "open-source" models. Despite this legislative attention on openness, the definition of open-source foundation models remains ambiguous. This paper models the strategic interactions among the creator of a general-purpose model (the generalist) and the entity that fine-tunes the general-purpose model to a specialized domain or task (the specialist), in response to regulatory requirements on model openness. We present a stylized model of the regulator's choice of an open-source definition to evaluate which AI openness standards will establish appropriate economic incentives for developers. Our results characterize market equilibria -- specifically, upstream model release decisions and downstream fine-tuning efforts -- under various openness regulations and present a range of effective regulatory penalties and open-source thresholds. Overall, we find the model's baseline performance determines when increasing the regulatory penalty vs. the open-source threshold will significantly alter the generalist's release strategy. Our model provides a theoretical foundation for AI governance decisions around openness and enables evaluation and refinement of practical open-source policies.