▁interval ▁type - 2 ▁f uz zy ▁sets ▁is ▁large , ▁whereas ▁the ▁literature ▁about ▁general ▁type - 2 ▁f uz zy ▁sets ▁is ▁much ▁smaller . ▁Both ▁kinds ▁of ▁f uz zy ▁sets ▁are ▁being ▁act ively ▁research ed ▁by ▁an ▁ever - g row ing ▁number ▁of ▁research ers ▁around ▁the ▁world ▁and ▁have ▁resulted ▁in ▁successful ▁employ ment ▁in ▁variety ▁of ▁domains ▁such ▁as ▁robot ▁control . ▁ ▁Form iller i ▁for ▁the ▁following ▁have ▁already ▁been ▁worked ▁out ▁for ▁interval ▁type - 2 ▁f uz zy ▁sets : ▁▁ ▁F uz zy ▁set ▁operations : ▁union , ▁intersection ▁and ▁complement ▁ ▁Cent roid ▁( a ▁very ▁widely ▁used ▁operation ▁by ▁pract ition ers ▁of ▁such ▁sets , ▁and ▁also ▁an ▁important ▁uncertainty ▁measure ▁for ▁them ) ▁ ▁Other ▁uncertainty ▁measures ▁[ f uzz iness , ▁cardinal ity , ▁variance ▁and ▁ske wn ess ▁and ▁uncertainty ▁bounds ▁ ▁Similar ity ▁ ▁Sub s eth ood ▁ ▁Em bed ded ▁f uz zy ▁sets ▁ ▁F uz zy ▁set ▁ranking ▁ ▁F uz zy ▁rule ▁ranking ▁and ▁selection ▁ ▁Type - redu ction ▁methods ▁ ▁F iring ▁intervals ▁for ▁an ▁interval ▁type - 2 ▁f uz zy ▁logic ▁system ▁▁ ▁F uz zy ▁weight ed ▁average ▁ ▁L ingu istic ▁weight ed ▁average ▁ ▁Syn thes izing ▁an ▁FO U ▁from ▁data ▁that ▁are ▁collected ▁from ▁a ▁group ▁of ▁subject ▁ ▁Inter val ▁Type - 2 ▁F uz zy ▁Log ic ▁Systems ▁Type - 2 ▁f uz zy ▁sets ▁are ▁finding