SIMAI 2025

Learning from data via overparameterization

  • Molinari, Cesare (unige)
  • Rosasco, Lorenzo (unige)
  • Villa, Silvia (unige)
  • Labarriere, Hippolyte (unige)
  • Vega, Cristian (universidad tarapacà)

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The goal of machine learning is to achieve a good prediction by exploiting training data and some a-priori information about the model. The most common methods to achieve the last objective are explicit and implicit regularization. In the first technique, a regularizer is explicitly introduced to find, among all the solutions, a good generalizing one. The second technique, i.e., implicit regularization, is based on the inductive bias intrinsically induced by the specific method used to optimize the parameters involved. Recently, the success of learning has been related to re- and over-parameterization, which are widely used - for instance - in neural network applications and the optimization method used. However, there is still an open question of how to find systematically what is the inductive bias hidden behind the model for a particular optimization scheme. The goal of this talk is to take a step in this direction by extensively studying many reparameterizations used in the state of the art and providing a common structure to analyze the problem in a unified way. We show that gradient descent on the empirical loss for many reparameterizations is equivalent, in the original problem, to a generalization of mirror descent. The mirror function depends on the reparameterization and introduces an inductive bias, which plays the role of the regularizer. Our theoretical results provide asymptotic behavior and convergence in the simplified setting of linear models.