@techreport{R-90-01, TITLE = {A Symbol Is Not a Symbol}, AUTHOR = {Nils Dahlb{\"a}ck}, YEAR = {1990}, NUMBER = {R-90-01}, INSTITUTION = ida, ADDRESS = idaaddr, ABSTRACT = {}, IDANR = {LiTH-IDA-R-90-01}, NOTE = {Also in Proc. of the 11th International Joint Conference on Artificial Intelligence (IJCAI'89), Detroit, Michigan, USA, August 20-25, 1989}