Definition:Millennium Problems

Definition
The Millennium Problems or Millennium Prize Problems are a collection of seven mathematical problems stated by the Clay Mathematics Institute in the year 2000.

Six of them remain unsolved.

They are as follows:
 * 1) P versus NP
 * 2) The Hodge Conjecture
 * 3) The Poincaré Conjecture (the only one of the seven to be solved)
 * 4) The Riemann Hypothesis
 * 5) Yang-Mills Existence and Mass Gap
 * 6) Navier-Stokes Existence and Smoothness
 * 7) The Birch and Swinnerton-Dyer Conjecture