What mathematical techniques M.C. Escher use?

M.C. Escher employed various mathematical techniques in his artwork, including aspects of geometry, symmetry, and tessellation. He often explored concepts such as infinity, perspective, and topology, creating intricate patterns that challenge the viewer's perception of space. His use of regular and semi-regular tiling, along with transformations like reflection and rotation, showcases a deep understanding of mathematical principles. Additionally, he incorporated impossible constructions and paradoxical imagery, reflecting a unique interplay between art and mathematics.