According to rough set theories, this paper puts forward a conception of the degree of credibility between objects and rules, and attempts to present a related relation prediction method.

Mr Buiter, who helped set interest rates at the Bank of England from 1997 to 2000, believes the latest academic theories had a profound influence there.

Initial theories set the disaster for May 2003, but when nothing happened the date was moved forward to the winter solstice in 2012, to coincide with the end of a cycle of the ancient Mayan calendar.