A new RL finding says the training harness may induce generalization

inductionheads · x · 2026-07-22

A new result argues that, for reinforcement learning with language models, the training harness can be responsible for much of the observed generalization.

Main claim

Transformers do not need a new intrinsic generalization ability to transfer across structurally similar tasks.
If the harness composes tasks well, the root model can learn the same trajectory for tasks that look different.
In that sense, the harness can induce generalization by grouping structurally similar trajectories together.

Practical note

The experiments were run with PrimeIntellect’s prime-rl library.
The harness uses verifiers today, with v1 support coming soon.
The library is open source.

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A new RL finding says the training harness may induce generalization

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