#### 1990

- Drinfeld is awarded a Fields Medal at the International Congress of Mathematicians in Kyoto, Japan for his work on quantum groups and for his work in number theory.

#### 1991

#### 1993

- Menasco and Thistlethwaite prove the knot theory conjecture known as "Tait's Second Conjecture", namely that any two reduced alternating diagrams of the same prime knot are related by a sequence of twists.

#### 1994

#### 1995

- A large prize is offered by banker Andrew Beal for a solution to the Beal Conjecture: the equation $x^{p} + y^{q} = z^{r}$ has no solutions for $p, q, r > 2$ and coprime integers $x, y, z$.

#### 1997

#### 1998

- Borcherds is awarded a Fields Medal for his work in automorphic forms and mathematical physics; Gowers receives one for his work in functional analysis and combinatorics; Kontsevich receives one for his work in algebraic geometry, algebraic topology, and mathematical physics; and McMullen receives one for his work on holomorphic dynamics and geometry of 3-dimensional manifolds.
- Thomas Hales proves Kepler's problem on sphere packing.

#### 1999

- The Great Internet Mersenne Prime Search project finds the 38th Mersenne prime: 26972593 -1.
- Conrad and Taylor prove the "Taniyama-Shimura conjecture". Wiles proved a special case in 1993 on his way to giving a proof of Fermat's Last Theorem.