Kummer–Vandiver conjecture

In mathematics, the Kummer–Vandiver conjecture, or Vandiver conjecture, states that a prime does not divide the class number of the maximal real subfield of the -th cyclotomic field. The conjecture was first made by Ernst Kummer, on 28 December 1849 and 24 April 1853 in letters to Leopold Kronecker, and independently rediscovered around 1920 by Philipp Furtwängler and Harry Vandiver.