set l = LTLB_WFF ;
set pairs = [:(LTLB_WFF **),(LTLB_WFF **):];
deffunc H1( FinSequence of LTLB_WFF ) -> Element of LTLB_WFF = 'not' ((con (nega $1)) /. (len (con (nega $1))));
deffunc H2( FinSequence of LTLB_WFF ) -> Element of LTLB_WFF = (con $1) /. (len (con $1));