Nikolai Ivanovich Lobachevsky (1792-1856) - creator of non-Euclidean geometry (Lobachevsky geometry). Rector of Kazan University (1827-46). The discovery of Lobachevsky (1826, published 1829-30), which was not recognized by contemporaries, revolutionized the idea of ​ ​ the nature of space, which was based on the teachings of Euclid for more than 2 thousand years, and had a huge impact on the development of mathematical thinking.