Bolyai-Gerwien, Bricard and Dehn theorems (Lecture 1, Part II)

Лекция 1, часть I, курс по многогранникам. Независимый Университет, зима 2021. https://www.math.ucla.edu/~pak/courses/IUM-Winter-2021/IUM-Winter-2021 This is Lecture 1, Part II of my 6-lecture course on polytopes (in Russian), IUM (Winter 2021).