It seems that the current implementation does not allow a FunctorCluster for a RedefinedFunctor. This may be a serious problem, if a function is redefined immediately ...
The order of articles in the NotationDirective is important. If two definitions of the same symbol from two different articles mentioned in notation are applicable ...
Despite the permissive defintion of the type Element http://mizar.uwb.edu.pl/JFM/Vol1/subset 1.abs.html#M1 the Frankel term still requires its arguments to widen ...