Research map / Time series / Long-term forecasting
Affirm: Interactive Mamba with Adaptive Fourier Filters for Long-term Time Series Forecasting
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Proposes Affirm, a lightweight time series forecaster combining an adaptive Fourier filter block (learnable thresholds plus global/local filters) with an interactive dual Mamba block, and reports SOTA-level accuracy with lower compute than Transformers.
Problem
Long-term time series forecasting (LTSF) where Transformers are computationally expensive, noise-sensitive, and overfit on small datasets, while linear and CNN models struggle with complex noisy data and long-range dependencies.
Approach
Replaces self-attention and feed-forward layers with an adaptive Fourier filter block (learnable low/high-pass thresholds and global/local frequency filters) and an interactive dual Mamba block using causal convolutions of two kernel sizes that cross-modulate each other, plus masked-autoencoder pretraining.
Key results
- Affirm achieves ETTh1 average MSE 0.411 vs PatchTST's 0.423 and Time-LLM's 0.408, with 9.78e+07 FLOPS versus Time-LLM's 7.3e+12.
- On Electricity (look-back 96, horizon 720), Affirm reaches MSE 0.216 with 1.7M parameters and 1.72G MACs, cutting MACs by 66.1% vs PatchTST.
- Ablation on ETTh1 shows removing AFFB raises average MSE from 0.411 to 0.434, and removing IDMB raises it to 0.423.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Add IDMB (ablation) | Affirm · ETTh1 (avg.) | MSE: 0.423 -> 0.411 | Helped |
| Add AFFB (ablation) | Affirm · ETTh1 (avg.) | MSE: 0.434 -> 0.411 | Helped |
| Add LPF (ablation) | Affirm · ETTh1 (avg.) | MSE: 0.421 -> 0.411 | Helped |
| Add HPF (ablation) | Affirm · ETTh1 (avg.) | MSE: 0.417 -> 0.411 | Helped |
| Add LPF and HPF (ablation) | Affirm · ETTh1 (avg.) | MSE: 0.422 -> 0.411 | Helped |
| Add self-supervised pretraining (ablation) | Affirm · ETTh1 (avg.) | MSE: 0.415 -> 0.411 | Helped |
| Use Affirm instead of PatchTST | ETTh1 · ETTh1 (avg.) | MSE: 0.428 -> 0.411 | Helped |
| Use Affirm instead of PatchTST | Electricity · Electricity (avg.) | MSE: 0.167 -> 0.157 | Helped |
| Use Affirm instead of PatchTST | ETTm2 · ETTm2 (avg.) | MSE: 0.264 -> 0.252 | Helped |
| Use Affirm instead of Dlinear | Exchange · Exchange (avg.) | MSE: 0.297 -> 0.356 | Hurt |
| Use Affirm instead of Time-LLM | ETTm1 · ETTm1 (avg.) | MSE: 0.329 -> 0.344 | Hurt |
Surprising findings
- Vanilla Mamba substituted into PatchTST underperforms on lower-frequency datasets such as ETTh2 and Exchange, though it is comparable on Weather and ETTm1.
Limitations
- Time-LLM (LLaMA-7B-based) achieves slightly better accuracy on several benchmarks, requiring far more compute.
- Only evaluated on standard multivariate LTSF benchmarks with a fixed look-back per dataset.
Experimental setup
Datasets: ETTh1 ETTh2 ETTm1 ETTm2 Electricity Exchange Traffic Weather
Benchmarks: ETTh1 ETTh2 ETTm1 ETTm2 Electricity Exchange Traffic Weather
Metrics: MSE MAE MACs parameters
Baselines: iTransformer PatchTST Crossformer DLinear RLinear TimeMixer TSLANet DTMamba Time-LLM GPT4TS
Builds on: Mamba PatchTST FiLM FreTS TSLANet
Closest papers by meaning
- Unlocking the Power of Patch: Patch-Based MLP for Long-Term Time Series Forecasting (AAAI 2025 · similarity 0.88)
- ARM: Refining Multivariate Forecasting with Adaptive Temporal-Contextual Learning (ICLR 2024 · similarity 0.88)
- Rethinking Fourier Transform from A Basis Functions Perspective for Long-term Time Series Forecasting (NeurIPS 2024 · similarity 0.87)
- CFPT: Empowering Time Series Forecasting through Cross-Frequency Interaction and Periodic-Aware Timestamp Modeling (ICML 2025 · similarity 0.87)
- OLinear: A Linear Model for Time Series Forecasting in Orthogonally Transformed Domain (NeurIPS 2025 · similarity 0.87)
- Towards a General Time Series Forecasting Model with Unified Representation and Adaptive Transfer (ICML 2025 · similarity 0.87)
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