Mayuka F. Kawaguchi Masaaki Miyakoshi Weakly Associative Functions on [0, 1] as Logical Connectives. 44-48 2004 conf/ismvl/2004 ISMVL http://csdl.computer.org/comp/proceedings/ismvl/2004/2130/00/21300044abs.htm db/conf/ismvl/ismvl2004.html#KawaguchiM04