Correspondence between subfields of a field extension K/F and subgroups of its automorphism group Gal(K/F). Classical corollary: quintic polynomials are not solvable in radicals.
Correspondence between subfields of a field extension K/F and subgroups of its automorphism group Gal(K/F). Classical corollary: quintic polynomials are not solvable in radicals.