Isadore Manuel Singer (1924 – 2021)

was an American mathematician. Singer is noted for his work with Michael Atiyah, proving the Atiyah–Singer index theorem in 1962, which states that for an elliptic differential operator on a compact manifold, the analytical index is equal to the topological index.

Among the awards he has received are the Bôcher Memorial Prize from the American Mathematical Society, the Steele Prize for Lifetime Achievement from the American Mathematical Society and the Abel Prize (2004) shared with Michael Atiyah.

Sir Michael Atiyah (1929 - 2019)

was a British-Lebanese Mathematician who grew up in Sudan and Egypt and studied in the UK.

The topological K-theory was discovered by Atiyah and Friedrich Hirzebruch who were inspired by Grothendieck's proof of the Grothendieck–Riemann–Roch theorem and Bott's work on the periodicity theorem.

He was awarded the Fields Medal in 1966.

Olga Alexandrowna Ladyschenskaja (1922-2004)

was a Soviet and Russian mathematician.

She was known for her work PDEs and fluid dynamics. She provided the first rigorous proofs of the convergence of a finite difference method for the Navier–Stokes equations.

Alexander Grothendieck (1928–2014)

was a German-born French mathematician.

He revolutionized algebraic geometry by developing powerful abstract concepts such as schemes, toposes, and motives. His work laid the foundation for much of modern geometry, number theory, and category theory.