Several results on de Morgan algebra and Kleene algebra of fuzzy logic

We present several results on de Morgan algebras and Kleene algebras of fuzzy logic. The main results include (1) a necessary and sufficient condition for a de Morgan algebra to be a Kleene algebra, (2) equivalence of some expressions, (3) some properties about de Morgan algebras with sup W/sup +/ and inf W/sup -/, (4) some properties of the de Morgan algebras which satisfy certain special conditions, (5) a method to obtain all fixed points of a de Morgan algebra and (6) extensions of some theorems on complete de Morgan algebras that have fixed points to the general case.