Research map / Large language models / Reasoning and chain of thought
HyPER: Bridging Exploration and Exploitation for Scalable LLM Reasoning with Hypothesis Path Expansion and Reduction
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Proposes HyPER, a training-free online expand-reduce controller for multi-path LLM decoding that adaptively chooses among none, single-token MoE routing aggregation, multi-token expansion, and branching, plus a length- and confidence-aware voting rule.
Problem
Test-time scaling with multi-path chain-of-thought needs an exploration-exploitation trade-off under fixed compute; rigid tree search and parallel sampling (self-consistency) handle it poorly, and answer selection by majority or confidence voting is fragile.
Approach
A closed-loop controller scores four actions (None, SingleToken, MultiToken, Branch) from lightweight pool statistics (confidence, entropy, consensus, diversity) every T steps; token-level refinement uses Gumbel-perturbed MoE routing with a two-pass diversity penalty and confidence-weighted logit aggregation; answers are chosen by a length-plus-confidence weighted vote under confidence pruning.
Key results
- On Qwen3-30B, HyPER reaches 94.0% on AIME24 and 95.3% on AIME25 versus 88.0% and 86.0% for SC, at 0.54x and 0.71x token cost.
- On OLMoE, HyPER reaches 86.5% on ARC-E at 0.36x token cost versus 80.1% for SC at 1.00x.
- Length-aware confidence voting improves AIME25 accuracy to 96.7% vs 86.7% for majority voting in the ablation (Qwen3-30B setup).
Surprising findings
- Confidence pruning inverts the typical length bias: surviving correct paths tend to be longer than incorrect ones.
- Confidence-weighted voting can be outvoted by noisy paths, motivating length-aware selection.
Limitations
- Relies on MoE routing diversity for the token-level primitive; dense-model evaluation is only a controller-only preliminary experiment.
- Length signal is only robust when coupled with confidence pruning, not universally valid.
- Hyperparameters (eta, lambda, T, weights) are set by hand and validated by sensitivity analysis only.
Experimental setup
Datasets: AIME24 AIME25 HMMT25 HLE GSM8K MATH500 ARC-C ARC-E
Benchmarks: AIME24 AIME25 HMMT25 HLE GSM8K MATH500 ARC-C ARC-E
Metrics: accuracy normalized token cost
Baselines: SC Self-Certainty DeepConf RoE
Builds on: DeepConf RoE Self-Consistency Tree of Thoughts
Closest papers by meaning
- DTS: Enhancing Large Reasoning Models via Decoding Tree Sketching (ICML 2026 · similarity 0.90)
- ArborKV: Structure-Aware KV Cache Management for Scaling Tree-based LLM Reasoning (ICML 2026 · similarity 0.89)
- What If We Allocate Test-Time Compute Adaptively? (ICML 2026 · similarity 0.89)
- Reasoning Path Compression: Compressing Generation Trajectories for Efficient LLM Reasoning (NeurIPS 2025 · similarity 0.89)
- Provable Test-Time Scaling for Beam Search in LLM Reasoning (NeurIPS 2026 · similarity 0.89)
- Bag of Tricks for Inference-time Computation of LLM Reasoning (NeurIPS 2025 · similarity 0.89)
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