Professor Smith and Marxist sociologists explain gentrification as a structural economic process; Humanistic Geographer, David Ley explains gentrification as a natural outgrowth of increased professional employment in the central business district (CBD), and the creative sub-class's predilection for city living. describes and deconstructs the TEAM committee's effort to rendering Vancouver, BC, Canada, a "livable city". The investigators Rose, Beauregard, Mullins, Moore "et al.", who base themselves upon Ley's ideas, posit that "gentrifiers and their social and cultural characteristics of crucial importance for an understanding of gentrification"—theoretical work Chris Hamnett criticized as insufficiently comprehensive, for not incorporating the "supply of dwellings and the role of developers [and speculators in the process".