Subsampling or subdata selection is a useful approach in large-scale statistical learning. Most existing studies focus on model-based subsampling methods which significantly depend on the model assumption. In this paper, we consider the model-free subsampling strategy for generating subdata from the...

The étale fundamental group of a connected scheme was introduced in a seminar before as a projective limit of finite étale coverings. We will explain the Galois theoretic point of view using unramified extensions. Source : Arapura’s notes “Introduction to Étale Cohomology “ Chapter 2