We define a category of formal CR manifolds in a purely algebraic way, study their basic properties, and prove the Baouendi–Ebenfelt–Rothschild minimality criterion in this setting. The objects of our category include deformations of classical CR manifolds (real-analytic or formal).
"Formal theory of Segre varieties." Illinois J. Math. 56 (1) 101 - 125, Spring 2012. https://doi.org/10.1215/ijm/1380287463