When did the woman, who was married 22 may 1657, cease to be the duchess?
CREATE TABLE "house_of_savoy" (
  "name" text,
  "father" text,
  "birth" text,
  "marriage" text,
  "became_duchess" text,
  "ceased_to_be_duchess" text,
  "death" text,
  "spouse" text
);
SELECT "ceased_to_be_duchess" FROM "house_of_savoy" WHERE "marriage"='22 may 1657';