SESSE: Sketch, Expand, Sort, Summarize, Evaluate -- LLM-as-Judge Evaluation via Structured Decomposition
Organizations: Apple
Abstract
LLM-as-judge evaluation reduces response quality assessment to a single holistic A/B preference choice, providing no mechanism to isolate which quality dimensions drove the preference or distinguish model errors from genuine label ambiguity. We propose SESSE (Sketch, Expand, Sort, Summarize, Evaluate), a training-free framework that decomposes holistic judgment into structured sub-questions mined directly from the judge's own error cases; requiring no oracle responses, task-specific rubrics, or fine-tuning. On RewardBench (n=1,000), SESSE achieves near-parity with the chain-of-thought baseline and is competitive with RISE-Judge-32B (92.7%), a fine-tuned specialist, while remaining fully training-free. Per-criterion vote evidence provides an interpretable audit trail for diagnosing label ambiguity and judge failure modes unavailable from a single holistic output token.
Figures & tables
| System | Holistic | SESSE | Tie% | |
|---|---|---|---|---|
| non-tie | tie | non-tie | ||
| Qwen2-VL-7B | 0.698 | 0.667 | 0.663 ‡ | 21.3% |
| Flash Lite | 0.880 | 0.679 | 0.820 ‡ | 2.6% |
| Gemini 2.5 Flash | 0.945 | 0.695 | 0.933 | 3.5% |
| RISE-Judge (32B) † Yu et al. (2025b) | 0.927 | — | ||
Appendix figures & tables3 assets
Supplementary material from the paper’s appendix.
Appendix
| Qwen2-VL-7B | Gemini 2.5 Flash | Flash Lite | |
|---|---|---|---|
| 1 | 0.626 | 0.923 | 0.790 |
| 2 | 0.648 | 0.933 | 0.804 |
| 3 | 0.663 | 0.927 | 0.801 |
| 5 | 0.644 | 0.932 | 0.820 |
| 7 | 0.645 | 0.929 | 0.817 |
| 10 | 0.643 | 0.930 | 0.819 |
| Config | SESSE acc ( ) | SESSE ( ) | |
|---|---|---|---|
| Qwen self-generated | 8 | 0.640 | 0.663 ( ) |
| Qwen Gemini bank | 14 | 0.637 | 0.663 ( ) |
| Config | Judge | Bank | Degradation (% val) | C1 (Ambiguous) | C2 (Decomposition) | C3 (Semantic equiv.) |
|---|---|---|---|---|---|---|
| Flash Lite | Flash Lite | self-generated | 105 (10.5%) | 49% | 26% | 26% |
| Gemini 2.5 Flash | Gemini 2.5 Flash | self-generated | 48 (4.8%) | 29% | 23% | 48% |
LLM Evaluation
Large language model evaluation measures what models can do, how reliably they do it, and whether benchmark scores predict real-world performance.
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