Go to TMLR homepageLinearly Controlled Language Generation with Performative Guarantees
Abstract: The increasing prevalence of Large Language Models (LMs) in critical applications highlights the need for controlled language generation methods that are not only computationally efficient but that also enjoy performance guarantees. To achieve this, we use a common model of concept semantics as linearly represented in an LM’s latent space. In particular, we take the view that natural language generation traces a trajectory in this continuous semantic space, realized by the language model’s hidden activations. This view permits a control-theoretic treatment of text generation in latent space, in which we propose a lightweight, gradient-free intervention that dynamically steers trajectories away from regions corresponding to undesired meanings. In particular, we propose to directly intervene the activations of the token that is being generated in embedding space in an online fashion. Crucially, we do not simply steer activations towards a desirable region. Instead, our method relies on classical techniques from control theory to precisely control activations in a context-dependent way, and guarantees that they are brought into a specific pre-defined region of embedding space that corresponds to allowed semantics. Our intervention is computed in closed-form according to an optimal controller formulation, minimally impacting generation
time. This control of the activations in embedding space allows for fine-grained steering of attributes of the generated sequence. We demonstrate the effectiveness of our approach on different objectives—toxicity avoidance and sentiment control—while maintaining text quality.
Submission Length: Long submission (more than 12 pages of main content)
Previous TMLR Submission Url: https://openreview.net/forum?id=RNLe2EKhmD
Changes Since Last Submission: Fixed the font (previous was desk-rejected due to an error in the template).
Assigned Action Editor: ~bo_han2
Submission Number: 5909
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