Smale's problems is a list of eighteen unsolved problems in mathematics proposed by Steve Smale in 1998[1] and republished in 1999.[2] Smale composed this list in reply to a request from Vladimir Arnold, then vice-president of the International Mathematical Union, who asked several mathematicians to propose a list of problems for the 21st century. Arnold's inspiration came from the list of Hilbert's problems that had been published at the beginning of the 20th century.