In Context Learning

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google3 min readCurated summary

Introducing TabFM: A zero-shot foundation model for tabular data

TabFM is a foundation model for tabular classification and regression that uses in-context learning instead of dataset-specific training. It processes an entire table in one forward pass, eliminating much of the usual hyperparameter tuning and feature engineering. The authors report that it performs competitively with or better than tuned tree-based models, with planned integration into BigQuery. ## The Challenge of Traditional Tabular ML - Tabular prediction supports applications such as churn prediction and fraud detection. - Algorithms including XGBoost, AdaBoost, and random forests remain widely used. - Building reliable models typically requires: - Hyperparameter optimization - Cross-validation - Domain-specific feature engineering - Repeated model training for each dataset ## Tabular Prediction Through In-Context Learning - TabFM treats tabular prediction as an in-context learning problem. - Users provide historical training rows and target rows together as a single input. - The model learns relationships between rows and columns during inference without updating model weights. - This enables zero-shot predictions on previously unseen datasets. ## Hybrid Architecture TabFM combines ideas from TabPFN and TabICL to address the two-dimensional, order-independent nature of tables. - **Alternating row and column attention** - Attends across both features and examples. - Learns feature interactions and dependencies directly from the table. - Reduces the need for manually engineered features. - **Row compression** - Converts the contextualized information for each row into a dense vector. - **In-context Transformer** - Operates on compressed row representations rather than the full table grid. - Reduces computation and supports larger datasets efficiently. ## Training with Synthetic Data - Large, diverse real-world tables are difficult to obtain because they often contain proprietary or sensitive information. - TabFM is trained entirely on hundreds of millions of synthetic datasets. - Structural causal models generate tables using varied random functions and relationships. - The goal is to reproduce the broad range of distributions and feature interactions found in real-world data. ## Benchmark Results and Model Variants - Evaluation used TabArena, an Elo-based benchmark covering: - 38 classification datasets - 13 regression datasets - Dataset sizes from 700 to 150,000 samples - **TabFM** - Works out of the box. - Produces predictions in one forward pass without tuning or cross-validation. - **TabFM-Ensemble** - Adds cross features and SVD-derived features. - Uses a 32-model ensemble with non-negative least squares to optimize weights. - Applies Platt scaling for classification calibration. - The authors state that TabFM consistently outperforms heavily tuned conventional supervised algorithms. ## Availability and BigQuery Integration - TabFM is available through Google’s Hugging Face and GitHub repositories. - Google plans to integrate it into BigQuery. - Users will be able to run regression and classification through an `AI.PREDICT` SQL command without specialized machine-learning expertise. TabFM’s main promise is to make high-quality tabular prediction as simple as supplying a dataset and requesting predictions. Its zero-shot approach could reduce the engineering burden of traditional workflows, though practical adoption will depend on benchmark reproducibility, inference costs, and performance across specific production datasets.

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googleOriginal article

Time series foundation models can be few-shot learners (opens in new tab)

Researchers at Google have introduced TimesFM-ICF, a foundation model that enables time-series forecasting to transition from zero-shot to few-shot learning via in-context fine-tuning. By utilizing continued pre-training and specialized separator tokens, the model learns to adapt to a handful of related examples at inference time without requiring the complex supervised fine-tuning typically needed for task-specific optimization. This approach effectively matches or exceeds the performance of specialized models while maintaining the flexibility of a general-purpose foundation model. ### Overcoming the Limitations of Zero-Shot Models * Traditional forecasting often requires building separate, specialized models for every unique task, which is resource-intensive and slow. * While zero-shot models like the original TimesFM provide immediate forecasts without task-specific training, they cannot incorporate relevant context, such as data from nearby sensors or similar historical patterns. * The In-Context Fine-tuning (ICF) approach allows the model to "learn" from a few examples provided at the time of prediction, similar to how Large Language Models (LLMs) use few-shot prompting. ### Architecture and the Common Separator Token * TimesFM-ICF utilizes a patched decoder architecture that tokenizes 32 contiguous timepoints into a single input token. * To prevent the model from conflating different data streams—such as separate store locations or distinct time periods—researchers introduced a "common separator token" as a digital boundary between examples. * The model processes these tokens through a transformer stack using causal self-attention (CSA), ensuring it learns from historical context without accidentally "peeking" into the future. * A shared multilayer perceptron (MLP) translates the processed output tokens back into a forecast spanning 128 timepoints. ### Performance Benchmarking and Results * The model was evaluated on 23 unseen datasets, using the Mean Absolute Scaled Error (MASE) metric to aggregate performance across diverse time-series tasks. * TimesFM-ICF demonstrated a significant performance boost over the original zero-shot TimesFM and other state-of-the-art foundation models like Moirai and Lag-Llama. * Test results showed that providing just a few in-context examples allowed the model to match the accuracy of supervised fine-tuning, which normally requires much more computational overhead and data curation. TimesFM-ICF represents a practical shift for businesses managing diverse data streams, offering a way to achieve high-accuracy forecasts by simply providing a few relevant historical examples. For those looking to optimize inventory or energy demands, this method provides the precision of a custom-tuned model with the deployment speed of a pre-trained foundation model.