Research map / Architectures and efficiency / RNNs and normalization
ANCRe: Adaptive Neural Connection Reassignment for Efficient Depth Scaling
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Shows theoretically on deep linear networks that residual-connection topology can induce exponential convergence gaps, and proposes ANCRe, which learns softmax-normalized weights over all possible shortcuts to reassign residual connections, yielding faster pre-training for LLaMA, DiT, and deep ResNets RL at <1% overhead.
Problem
Residual connections are almost always placed in a fixed cascaded layout, yet their topology may strongly affect optimization and depth utilization in deep networks; no principled way exists to choose a good topology.
Approach
Parameterize all possible inter-layer shortcuts i:j with learnable coefficients normalized by a softmax over incoming connections (ingoing normalization), so the model learns a data-driven residual topology on the fly with only K(K+1)/2 extra parameters.
Key results
- ANCRe reduces LLaMA validation perplexity by 0.73 ± 0.33 on average over cascaded residuals and matches baseline perplexity with on average 34.3% fewer training iterations.
- On DiT-B/2 with cfg=1.5, ANCRe improves FID from 22.41 to 20.53.
- ANCRe adds negligible overhead: throughput drop <1% and peak memory increase below 0.01GB; 16-layer ResNet with ANCRe matches or surpasses a 4x deeper ResNet in RL.
Surprising findings
- Learnable coefficients over all shortcuts with constant weights (or learnable cascaded residuals) either diverge or underperform, indicating gains come from the combination of topology and adaptive coefficients.
- Frozen learned topology retrained from scratch retains nearly all gains.
Limitations
- Theory limited to deep linear networks under gradient flow with whitened data; nonlinear extension left to future work.
- Benefits appear mainly for deep networks; gains on shallower DiT are smaller.
- Sparse variants needed for gradient checkpointing and pipeline parallelism costs; long-range shortcuts increase recomputation and communication.
Experimental setup
Datasets: C4 ImageNet-1K Gymnasium Humanoid Gymnasium Ant_Big_Maze Gymnasium Arm_Push_Hard Gymnasium Arm_Binpick_Hard
Benchmarks: C4 validation perplexity ImageNet FID-50K Gymnasium goal-reaching tasks time-at-goal
Metrics: perplexity FID sFID inception score precision recall time-at-goal training throughput peak GPU memory
Baselines: cascaded residual connections hyper-connections (HC) manifold-constrained hyper-connections (mHC) GaLore
Builds on: ResNet Transformer hyper-connections GaLore contrastive RL
Closest papers by meaning
- Revisiting Residual Connections: Orthogonal Updates for Stable and Efficient Deep Networks (NeurIPS 2025 · similarity 0.84)
- Residual Alignment: Uncovering the Mechanisms of Residual Networks (NeurIPS 2023 · similarity 0.84)
- Adaptive Depth Networks with Skippable Sub-Paths (NeurIPS 2024 · similarity 0.84)
- Tensor Programs VI: Feature Learning in Infinite Depth Neural Networks (ICLR 2024 · similarity 0.84)
- Depthwise Hyperparameter Transfer in Residual Networks: Dynamics and Scaling Limit (ICLR 2024 · similarity 0.83)
- Neural Collapse is Globally Optimal in Deep Regularized ResNets and Transformers (NeurIPS 2025 · similarity 0.82)
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