theorem Th63:
  mlt(p,<*A*>)=<*p/.1*A*>
proof
A1: dom mlt(p,<*A*>) = dom <*A*> by Def9
    .= Seg 1 by FINSEQ_1:38;
  then 1 in dom mlt(p,<*A*>);
  then
A2: mlt(p,<*A*>).1 = p/.1*(<*A*>.1) by Def9
    .= p/.1*A;
  len mlt(p,<*A*>)=1 by A1,FINSEQ_1:def 3;
  hence thesis by A2,FINSEQ_1:40;
end;
