# Atiyah, Michael Francis (1929–2019)

Michael Atiyah was an English mathematician who contributed to many topics
in mathematics, notably dealing with the relationships between geometry
and analysis. In topology,
he developed **K-theory**. He proved the **index theorem** on the number of solutions of elliptic differential equations, linking differential
geometry, topology, and analysis – a theorem that has been usefully
applied to quantum theory. Atiyah was influential in initiating work on gauge theories and applications to
nonlinear differential equations, and in making links between topology and quantum field theory. Theories
of superspace and supergravity, and string
theory, were all developed using ideas introduced by him.