reserve A for QC-alphabet;
reserve k,n,m for Nat;
reserve P for QC-pred_symbol of A;
reserve F for Element of QC-WFF(A);
reserve Q for QC-pred_symbol of A;
reserve F, G for (Element of QC-WFF(A)), s for FinSequence;
reserve p for Element of QC-WFF(A);

theorem Th14:
  p is negative implies len @the_argument_of p < len @p
proof
  assume
A1: p is negative;
  then consider q being Element of QC-WFF(A) such that
A2: p = 'not' q;
  len @p = len <*[1, 0]*> + len @q by A2,FINSEQ_1:22
    .= len @q + 1 by FINSEQ_1:40;
  then len @q < len @p by NAT_1:13;
  hence thesis by A1,A2,Def24;
end;
