PAC Bound

Creator
Creator
Seonglae ChoSeonglae Cho
Created
Created
2025 Mar 23 23:28
Editor
Edited
Edited
2025 Jun 2 16:29

Generalization bounds are a safety check

They give a theoretical guarantee on the performance of a learning algorithm on any unseen data.
Just because a model fits well on training data doesn't guarantee it will perform well in practice. However, we can mathematically bound how well it generalizes.
The PAC-Bayes Bound provides a probabilistic guarantee for this, showing that the difference between training error and test error can be expressed as a complexity term based on the
Divergence Distance
between the
Prior
and
Posterior
. This can be simply expressed as follows:
where is sample count and is the probability of being misled by the training set.
  • Bound depends on the distance between prior and posterior
  • Better prior (closer to posterior) would lead to tighter bound
  • Learn the prior P with part of the data
  • Introduce the learnt prior in the bound
Dziugaite and Roy (2017), Neyshabur et al. (2017) have derived some of the tightest deep learning bounds in this way
 
 
 
 
2017
Exploring Generalization in Deep Learning
With a goal of understanding what drives generalization in deep networks, we consider several recently suggested explanations, including norm-based control, sharpness and robustness. We study how...
Exploring Generalization in Deep Learning
Computing Nonvacuous Generalization Bounds for Deep (Stochastic)...
One of the defining properties of deep learning is that models are chosen to have many more parameters than available training data. In light of this capacity for overfitting, it is remarkable...
Computing Nonvacuous Generalization Bounds for Deep (Stochastic)...
2024
arxiv.org
openreview.net
 
 

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