lotfi zadeh gzrdaeecsberkeleyedu dear concept similarity one basic concepts human cognition similarity plays essential role taxonomy recognition casebased reasoning many fields enormous literature yet many aspects concept similarity eluded formalization concretely thesis like put table exist valid generalpurpose definition similarity exist many specialpurpose definitions employed success cluster analysis search classification recognition diagnostics typically point departure definitions similarity following formulation given descriptions two objects b asked assess degree similarity b usually descriptions b form lists attributes features b respective values frequently employed measures similarity tversky jacard spirit problem formulation degree similarity assessed given descriptions b explicitly implicitly case point wellknown story buffalo given four objects b c asked tell object different three objects aids herpes gonorrhea condominium buffalo obvious candidate condominium buffalo correct answer gonorrhea one get rid gonorrhea possible get rid aids herpes condominium buffalo clearly degree similarity depends purpose andor context mind let us reformulate definition similarity attribute allowed take undefined value loss generality assuming b associated identical lists attributes r1 rn let us assume attribute ri associate degree similarity si attribute values ria rib furthermore given purpose associate attribute degree importance wi problem reduces aggregation list si wi sn wn single degree similarity formulation framework definition may called general purpose definition furthermore serious difficulty degrees similarity ria rib rja rjb may low 0 yet degree similarity function ria rib function rja rjb may high example ri length rj width b may different lengths widths yet area conclusion formulation valid generalpurpose definition similarity challenging problem definition point valid generalpurpose definition literature regards lotfi lotfi zadeh professor graduate school director berkeley initiative soft computing bisc teloffice 510 6424959 fax office 510 6421712 fri 08 aug 2008 011852 0800 uai define similarity