  The class of radial fuzzy systems is introduced. The fuzzy systems in this
class use radial functions to implement membership functions of fuzzy sets and
exhibit a shape preservation property in antecedents of their rules. The
property is called the radial property. It enables the radial fuzzy systems to
have their computational model mathematically tractable under both conjunctive
and implicative representations of their rule bases. Coherence of radial
implicative fuzzy systems is discussed and a sufficient condition for coherence
is stated.
