TROY, N.Y. - Edd Hifeng barely merits a second glance in "Second Life." A steel-gray robot with lanky limbs and linebacker shoulders, he looks like a typical avatar in the popular virtual world. But Edd is different. His actions are animated not by a person at a keyboard but by a computer. Edd is a creation of artificial intelligence, or AI, by researchers at Rensselaer Polytechnic Institute, who endowed him with a limited ability to converse and reason. It turns out "Second Life" is more than a place where pixelated avatars chat, interact and fly about. It's also a frontier...