Can an iterative draft–revise solver that repeatedly updates a latent scratchpad outperform far larger autoregressive LLMs on ARC-AGI? Samsung SAIT (Montreal) has released Tiny Recursive Model (TRM)—a two-layer, ~7M-parameter recursive reasoner that reports 44.6–45% test accuracy on ARC-AGI-1 and 7.8–8% on ARC-AGI-2, surpassing results reported for substantially larger language models such as DeepSeek-R1, o3-mini-high, and Gemini 2.5 Pro on the same public evaluations. TRM also improves puzzle benchmarks Sudoku-Extreme (87.4%) and Maze-Hard (85.3%) over the prior Hierarchical Reasoning Model (HRM, 27M params), while using far fewer parameters and a simpler training recipe.
What’s exactly is new?
TRM removes HRM’s two-module hierarchy and fixed-point gradient approximation in favor of a single tiny network that recurses on a latent “scratchpad” (z) and a current solution embedding (y):
- Single tiny recurrent core. Replaces HRM’s two-module hierarchy with one 2-layer network that jointly maintains a latent scratchpad 𝑧 z and a current solution embedding 𝑦 y. The model alternates: think: update 𝑧 ← 𝑓 ( 𝑥 , 𝑦 , 𝑧 ) z←f(x,y,z) for 𝑛 n inner steps; act: update 𝑦 ← 𝑔 ( 𝑦 , 𝑧 ) y←g(y,z).
- Deeply supervised recursion. The think→act block is unrolled up to 16 times with deep supervision and a learned halting head used during training (full unroll at test time). Signals are carried across steps via (y,z)(y, z)(y,z).
- Full backprop through the loop. Unlike HRM’s one-step implicit (fixed-point) gradient approximation, TRM backpropagates through all recursive steps, which the research team find essential for generalization.
Architecturally, the best-performing setup for ARC/Maze retains self-attention; for Sudoku’s small fixed grids, the research team swap self-attention for an MLP-Mixer-style token mixer. A small EMA (exponential moving average) over weights stabilizes training on limited data. Net depth is effectively created by recursion (e.g., T = 3, n = 6) rather than stacking layers; in ablations, two layers generalize better than deeper variants at the same effective compute.
Understanding the Results
- ARC-AGI-1 / ARC-AGI-2 (two tries): TRM-Attn (7M): 44.6% / 7.8% vs HRM (27M): 40.3% / 5.0%. The research team-reported LLM baselines: DeepSeek-R1 (671B) 15.8% / 1.3%, o3-mini-high 34.5% / 3.0%, Gemini 2.5 Pro 37.0% / 4.9%; larger bespoke Grok-4 entries are higher (66.7–79.6% / 16–29.4%).
- Sudoku-Extreme (9×9, 1K train / 423K test): 87.4% with attention-free mixer vs HRM 55.0%.
- Maze-Hard (30×30): 85.3% vs HRM 74.5%.
These are direct-prediction models trained from scratch on small, heavily augmented datasets—not few-shot prompting. ARC remains the canonical target; broader leaderboard context and rules (e.g., ARC-AGI-2 grand-prize threshold at 85% private set) are tracked by the ARC Prize Foundation.
Why a 7M model can beat much larger LLMs on these tasks?
- Decision-then-revision instead of token-by-token: TRM drafts a full candidate solution, then improves it via latent iterative consistency checks against the input—reducing exposure bias from autoregressive decoding on structured outputs.
- Compute spent on test-time reasoning, not parameter count: Effective depth arises from recursion (emulated depth ≈ T·(n+1)·layers), which the researchers show yields better generalization at constant compute than adding layers.
- Tighter inductive bias to grid reasoning: For small fixed grids (e.g., Sudoku), attention-free mixing reduces overcapacity and improves bias/variance trade-offs; self-attention is kept for larger 30×30 grids.
Key Takeaways
- Architecture: A ~7M-param, 2-layer recursive solver that alternates latent “think” updates 𝑧 ← 𝑓 ( 𝑥 , 𝑦 , 𝑧 ) z←f(x,y,z) and an “act” refinement 𝑦 ← 𝑔 ( 𝑦 , 𝑧 ) y←g(y,z), unrolled up to 16 steps with deep supervision; gradients are propagated through the full recursion (no fixed-point/IFT approximation).
- Results: Reports ~44.6–45% on ARC-AGI-1 and ~7.8–8% on ARC-AGI-2 (two-try), surpassing several much larger LLMs as cited in the research paper’s comparison (e.g., Gemini 2.5 Pro, o3-mini-high, DeepSeek-R1) under the stated eval protocol.
- Efficiency/Pattern: Demonstrates that allocating test-time compute to recursive refinement (depth via unrolling) can beat parameter scaling on symbolic-geometric tasks, offering a compact, from-scratch recipe with publicly released code.
This research demonstrates a ~7M-parameter, two-layer recursive solver that unrolls up to 16 draft-revise cycles with ~6 latent updates per cycle and reports ~45% on ARC-AGI-1 and ~8% (two-try) on ARC-AGI-2. The research team released code on GitHub. ARC-AGI remains unsolved at scale (target 85% on ARC-AGI-2), so the contribution is an architectural efficiency result rather than a general reasoning breakthrough.
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