Add comprehensive README
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README.md
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# π LiquidDiffusion
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**A novel attention-free image generation model based on Liquid Neural Networks**
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[](https://colab.research.google.com/github/huggingface/notebooks/blob/main/liquid-diffusion/LiquidDiffusion_Training.ipynb)
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## What is this?
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LiquidDiffusion is a **first-of-its-kind** image generation model that replaces attention with **Parallel CfC (Closed-form Continuous-depth) blocks** from Liquid Neural Network research. No existing paper combines LNNs with image generation β this fills that gap.
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### Key Properties
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- β
**Zero attention layers** β fully convolutional + liquid time-gating
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- β
**Fully parallelizable** β no ODE solvers, no sequential scanning, no recurrence
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- β
**Fits 16GB VRAM** β tiny config runs 256px at batch=8 on T4 GPU
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- β
**Simple training** β Rectified Flow (MSE velocity prediction, no noise schedule)
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- β
**Adaptive processing** β CfC time-gating naturally adapts to noise level
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## Architecture
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```
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Input (noisy image) β Conv Stem
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β Encoder [LiquidDiffusionBlock Γ N per stage, with downsampling]
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β Bottleneck [LiquidDiffusionBlock Γ 2]
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β Decoder [LiquidDiffusionBlock Γ N per stage, with upsampling + skip fusion]
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β Conv Head β Velocity prediction
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```
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Each **LiquidDiffusionBlock** contains:
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1. **AdaLN** β timestep conditioning via learned scale/shift
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2. **ParallelCfCBlock** β the core liquid neural network layer
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3. **MultiScaleSpatialMix** β 3Γ3+5Γ5+7Γ7 depthwise conv + global pooling (replaces attention)
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4. **FeedForward** β channel mixing via 1Γ1 conv
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### The ParallelCfC Block (Novel Contribution)
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Based on CfC Eq.10: `x(t) = Ο(-fΒ·t) β g + (1 - Ο(-fΒ·t)) β h`
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```python
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# Three CfC heads from shared backbone
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f = f_head(backbone) # time-constant gate
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g = g_head(backbone) # "from" state
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h = h_head(backbone) # "to" state (attractor)
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# CfC time-gating with diffusion timestep
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gate = sigmoid(time_a(t_emb) * f - time_b(t_emb))
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cfc_out = gate * g + (1 - gate) * h
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# Liquid relaxation residual (from LiquidTAD)
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Ξ± = exp(-softplus(Ο) * |t_emb_mean|)
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output = Ξ± * input + (1 - Ξ±) * cfc_out
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```
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**Key insight**: The diffusion timestep `t` IS the liquid time constant. When noise is high, the gate saturates differently than when noise is low, giving the network input-dependent processing without attention.
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## Model Configs
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| Config | Channels | Blocks | Params | 256px VRAM | Best For |
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|--------|----------|--------|--------|------------|----------|
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| tiny | [64, 128, 256] | [2, 2, 4] | ~23M | ~6 GB | Quick experiments, T4 |
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| small | [96, 192, 384] | [2, 3, 6] | ~69M | ~10 GB | Quality 256px, T4/A10G |
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| base | [128, 256, 512] | [2, 4, 8] | ~154M | ~16 GB | 512px, A100 |
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## Training
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### Quick Start (Colab)
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1. Open the notebook: `LiquidDiffusion_Training.ipynb`
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2. Set your config in the first code cell
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3. Run all cells
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4. Training samples appear every 500 steps
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### Training Objective: Rectified Flow
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```python
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# Simple MSE on velocity β no noise schedule to tune!
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x_t = (1 - t) * x0 + t * noise # linear interpolation
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v_target = noise - x0 # constant velocity target
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loss = MSE(model(x_t, t), v_target) # that's it!
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```
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### Sampling: Euler ODE
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```python
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z = randn(B, 3, H, W) # start from noise
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for t in linspace(1, 0, steps): # integrate backward
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z = z - model(z, t) * dt # Euler step
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```
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## References
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This work is grounded in deep research across 10+ papers:
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| Paper | Key Contribution Used |
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|-------|----------------------|
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| [CfC Networks (Hasani et al., Nature MI 2022)](https://arxiv.org/abs/2106.13898) | CfC Eq.10 time-gating, parallelizable closed-form |
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| [LTC Networks (Hasani et al., AAAI 2021)](https://arxiv.org/abs/2006.04439) | Liquid time-constant ODE, stability theorems |
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| [LiquidTAD (2024)](https://arxiv.org/abs/2604.18274) | Parallel liquid relaxation (removed recurrence) |
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| [USM (CVPR 2025)](https://arxiv.org/abs/2504.13499) | U-Net + SSM architecture for diffusion |
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| [DiffuSSM (2023)](https://arxiv.org/abs/2311.18257) | SSM replaces attention in diffusion (FID=2.28) |
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| [Rectified Flow (Liu et al., ICLR 2023)](https://arxiv.org/abs/2209.03003) | Simple velocity prediction training |
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| [Neural Circuit Policies (2020)](https://arxiv.org/abs/2006.04439) | Sparse wiring, parameter efficiency |
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## Files
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```
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βββ liquid_diffusion/
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β βββ __init__.py # Package exports
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β βββ model.py # Full model architecture
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β βββ trainer.py # Rectified Flow trainer + dataset utils
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βββ LiquidDiffusion_Training.ipynb # Complete Colab notebook
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βββ test_model.py # Test suite
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βββ README.md # This file
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```
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## License
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MIT
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