Training only the root token enables efficient adaptive reasoning

Root-token Policy Optimization (RPO) trains only the initial gating token of large reasoning models, cutting adaptive‑thinking training cost to about 2% of prior methods.

Academic
Taehyeon Kim · Hyunsoo Lee · Youngsoo Jang · Moontae Lee

LG AI Research · UNIST · University of Illinois Chicago

Research Digest··3 min read
The authors introduce Root‑token Policy Optimization (RPO), a framework that allows large reasoning models (LRMs) to decide adaptively whether to engage in explicit reasoning by optimizing only the first token (the root token) that gates the reasoning process.

The authors propose a two‑stage method.

Why this paper

From UNIST and 2 others

In one line

Root-token policy optimization teaches reasoning models when to think while using about 2% of the training compute required by prior adaptive-reasoning methods.

What we could check

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Research Digest

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