Training intuition: final = base + (rlvr − base), midtrain collapses into a task vector
voooooogel · x · 2026-10-29
The author shares a clean intuition for LLM training pipelines: the ideal order base → midtrain → RLVR means each arrow adds to the weights, so midtrain − base and rlvr − midtrain are task vectors, yielding final = base + (midtrain − base) + (rlvr − midtrain) = base + (rlvr − base).
He notes the stages are theoretically entangled by their ordering, but this decomposition offers a composable way to think about midtraining and RL fine-tuning as additive weight deltas.
Related event: Multi-stage LLM training decomposes into additive task vectors(2 posts)→
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