Trial Parallelism Is 65.5% of Parallelizable Reasoning Compute, and Parason Converts It Into 1.7x Wall-Clock Speedup

arXiv 2608.24658·medium signalXBlueskyLinkedInCopy link

Prior parallel-reasoning systems focus on subtask parallelism, decomposing a task into independently solvable chunks, and miss what the authors measure as the larger share: trial parallelism, where multiple speculative attempts explore, verify and aggregate competing hypotheses at once, accounting for 65.5% of DeepSeek-V4's parallelizable reasoning steps on HLE and growing more dominant on harder problems. Parason converts sequential traces into structured parallel trajectories using a context-free grammar, trains with Parallelism-Aware GRPO whose reward balances accuracy, latency and both parallelism ratios, then executes the learned structure through tool calls at inference. On AIME24 and AIME25 it averages roughly 1.7x acceleration with competitive accuracy.