E. Karni et Z. Safra, The hexagon condition and additive representation for two dimensions: An algebraic approach, J MATH PSYC, 42(4), 1998, pp. 393-399
Within the algebraic approach the Thomsen condition may be replaced with th
e hexagon condition to imply the existence of additive representation for t
wo dimensions. In some models the Thomsen condition does not have a natural
interpretation whereas the hexagon condition does, which makes it better s
uited for axiomatic theories. (C) 1998 Academic Press.