In the early stages of his career, Zalewski made significant contributions to the field of mathematics. His notable debut achievements and brilliant performances in various areas of mathematics have earned him widespread recognition.

One of his most notable achievements was his work on the theory of linear equations. He developed a new method for solving systems of linear equations that has become widely used in modern mathematics. This breakthrough helped to establish him as one of the leading mathematicians of his time.

Another notable achievement of Zalewski's early career was his work on the theory of group actions. He introduced a new approach to understanding group actions, which has had a profound impact on the field of mathematics. This work laid the foundation for many subsequent developments in the area.

Zalewski's brilliance in mathematics was evident in his performances at the highest level. He won numerous awards and accolades throughout his career, including the Fields Medal, one of the most prestigious prizes in mathematics. His exceptional talent and dedication to his craft were recognized by peers and colleagues alike.

Throughout his career, Zalewski continued to make groundbreaking contributions to the field of mathematics. His legacy as a pioneering figure in the study of linear algebra and group theory is cemented in the annals of mathematical history.