theorem Th10: (con <*>LTLB_WFF)/.(len con <*>LTLB_WFF) = TVERUM
  proof
A1: len <*>l = 0;
    then con <*>l = <*TVERUM*> by Def2;
    then A2: len con <*>l = 1 by FINSEQ_1:39;
    hence kon(<*>l) = (con <*>l).(len con <*>l) by FINSEQ_4:15
    .= <*TVERUM*>.(len con <*>l) by Def2,A1
    .= TVERUM by A2;
  end;
