Sept. 29 (UPI) -- A Hong Kong pro-democracy activist living in self-exile was barred from entry to Singapore after arriving on Saturday despite the country having issued him a visa. Nathan Law came to Singapore to speak at a conference. He had been issued a visa for the closed door, invitation-only event. But when he arrived, he was questioned for four hours then denied entry. He was sent on a flight Sunday back to San Francisco, which is where his plane to Singapore had departed from. Law