K2

K² · Artificial intelligence

A forecasting model that never has to start over when new data arrives

The authors introduce TiRex-2, a recurrent xLSTM-based time series foundation model that generalizes the univariate TiRex to multivariate forecasting with both past and future covariates.

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Patrick Podest, Marco Pichler, Elias Bürger et al.

10 authors · cs.LG

arXiv preprintArtificial intelligenceJul 2026 · ~70s read

The 30-second scan

Most forecasting AIs have an expensive habit: every time a new data point shows up, they re-read the entire history from scratch to update their prediction.

  1. Existing Transformer-based time series foundation models capture cross-variate dependencies but incur quadratic complexity in context length and require full-history recomputation as new observations arrive.
  2. TiRex-2 uses a memory-centric recurrent design that operates at constant per-patch cost under streaming.
  3. The model combines a bidirectional time mixer with an asymmetric grouped-attention variate mixer, enabling integration of future-known covariates while preserving strict causality over target variables.
38.4M active parameters used in univariate modean additional 44.1M parameters activated for multivariate forecasting