George Mostow
![George Mostow](https://upload.wikimedia.org/wikipedia/en/thumb/b/b7/George_Mostow.jpg/150px-George_Mostow.jpg)
The rigidity phenomenon for lattices in Lie groups he discovered and explored is known as Mostow rigidity. His work on rigidity played an essential role in the work of three Fields medalists, namely Grigori Margulis, William Thurston, and Grigori Perelman. In 1993 he was awarded the American Mathematical Society's Leroy P. Steele Prize for Seminal Contribution to Research. In 2013, he was awarded the Wolf Prize in Mathematics "for his fundamental and pioneering contribution to geometry and Lie group theory." Provided by Wikipedia