This is the symbol representing the set of possible models.
This is the symbol representing the set of possible models. The set is often formed from a particular class of models (e.g. polynomials of any degrees).
The symbol \( \mathcal{H} \) denotes the set of possible models, often from a particular class like "polynomials of any degree" or "multi-layer perceptron networks". For any learning algorithm, \( \mathcal{H} \) indicates the space where an optimal model may be found.
Jaeger, H. (n.d.). Neural Networks (AI) (WBAI028-05) Lecture Notes BSc program in Artificial Intelligence. Retrieved April 20, 2024, from https://www.ai.rug.nl/minds/uploads/LN_NN_RUG.pdf