Doubly Eponymous Things by HensleyB

Question 9

In 2000, the Clay Mathematics Institute posed seven so-called "Millennium Prize Problems" and offered $1,000,000 for the solution to each. Only one of those problems, proof of the Poincaré conjecture, has since been solved. Three of the remaining six problems fit the theme of this quiz-- name any one. The surnames of the two relevant individuals will suffice.

Yang–Mills OR Navier-Stokes OR Birch and Swinnerton-Dyer