Sendov's conjecture

Etymology
Named after Bulgarian mathematician.

Proper noun

 * 1)  A conjecture concerning the relationship between the locations of roots and critical points of a polynomial function of a complex variable. It states that for a polynomial $$ f(z) = (z - r_1)\cdots (z-r_n),\qquad (n\ge 2) $$ with all roots r1, ..., rn inside the closed unit disk |z| ≤ 1, each of the n roots is at a distance no more than 1 from at least one critical point.