# Rough set thesis + /pdf

A fuzzy interval is an uncertain [ clarification needed ] set A ~ ⊆ R {\displaystyle {\tilde {\mathit {A}}}\subseteq \mathbb {R} } with a mean interval [ clarification needed ] whose elements possess the membership function value μ A ( x ) = 1 {\displaystyle \mu _{A}(x)=1} . As in fuzzy numbers, the membership function must be convex , normalized , at least segmentally continuous . [9]