Name the reason for 20 july 1031
CREATE TABLE "capetian_associate_kings" (
  "co_king" text,
  "relationship_to_monarch" text,
  "crowned" text,
  "co_kingship_ceased" text,
  "reason" text,
  "monarch" text
);
SELECT "reason" FROM "capetian_associate_kings" WHERE "co_kingship_ceased"='20 July 1031';