Dear Colleagues: Efficiency is a ambiguous concept in economics, I would have a speech in the Eastern Economic Association Annual Meetings, in Boston.My speech would focus on efficiency in the view of economic thought.I would try to rational reconstruct the efficiency through emergent property.I wonder how efficiency has been used in the history of economics.Your assistance will be appreciated. Sincerely Yi Hu -------------------------------------------------- View my research on my SSRN Author page: http://ssrn.com/author=1621246