NTH

Selection Is Not Learning: Choosing Model Futures

AuthorsHaoyi Yang, Kshitij Mishra, Nils Lukas, Salem Lahlou

AffiliationsMohamed bin Zayed University of Artificial Intelligence, Abu Dhabi, UAE

October 22, 2026 2 min read
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The one-line take

A framework for self-evolving language models that checks whether an update actually helps before inheriting it, while retaining useful experience from other updates.

Key results

62.5%
Skill Self-Play updates without NLL gain

Share of audited updates on verified tasks that did not improve correct-target negative log-likelihood.

68–83%
Reduction in harmful accepted updates

HEIR COMMIT reduction relative to random inheritance at the same acceptance rate.

5.3%
Math average gain over Agent0

EVO HEIR’s reported relative math-average improvement across four backbones.

45
Benchmark–backbone comparisons won

EVO HEIR beats Agent0 on 45 of 48 comparisons.

1.93
Recovery gain over direct fine-tuning

Average improvement in percentage points using the same references.

What the paper found

Self-evolving systems such as R-Zero, Agent0, and Skill Self-Play often select tasks that appear learnable, then inherit every resulting update. The paper finds that task selection does not reliably predict whether training helps: 62.5% of audited Skill Self-Play updates on verified tasks did not improve correct-target negative log-likelihood. HEIR COMMIT addresses this selection-to-update gap by freezing a proposed successor and committing it only if it beats the current model on fresh evaluation probes. Across three hosts, it reduces the harmful share of accepted updates by 68–83%. EVO HEIR goes further by separating parameter inheritance from experience inheritance: it screens for a model recipient, uses current and archived solutions to repair that recipient’s failures while preserving successes, then independently confirms the resulting model. Across Qwen3, OLMo-3, and Google’s Gemma-4-E4B-it, EVO HEIR raises the math average by 5.3% relative to Agent0 and beats Agent0 on 45 of 48 benchmark–backbone comparisons. Recovery also outperforms direct fine-tuning on the same references by 1.93 percentage points on average, showing that useful experience can persist even when its source model is rejected.

Original abstract

Self-evolving language models train on tasks they generate, so every round must decide which updated model the next round inherits. Current loops such as R-Zero, Agent0, and Skill Self-Play make this decision through the task, admitting tasks that look learnable and inheriting every resulting update. We identify a selection-to-update gap in these loops, where a task that looks learnable need not produce a useful update. Most updates on verified tasks fail to make correct answers more likely, yet these loops inherit them all. HeirCommit freezes the updated model and uses fresh evaluation questions to decide whether to inherit it or retain the current model. EvoHeir separates parameter inheritance from experience inheritance, using current and archived experience to repair failures and preserve successes before final confirmation. Our analysis characterizes selection-induced optimism and decomposes regret into selection, absorption, and confirmation errors. HeirCommit cuts the harmful share of accepted updates by 68-83% relative to random inheritance at the same acceptance rate. Across four backbones, EvoHeir achieves the best mathematics and general-reasoning averages, raising the math average by 5.3% relative to the strongest baseline, Agent0. The framework lets useful experience persist even when the model that produced it is not inherited.

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