theorem
  A is symmetry_circulant & n>0 implies A@ is symmetry_circulant
proof
  assume that
A1: A is symmetry_circulant and
A2: n>0;
  consider p being FinSequence of D such that
A3: len p=width A and
A4: A is_symmetry_circulant_about p by A1;
  width A=n & len A=n by MATRIX_0:24;
  then width (A@)=len p by A2,A3,MATRIX_0:54;
  then consider p being FinSequence of D such that
A5: len p = width (A@) & A@ is_symmetry_circulant_about p by A2,A4,Th6;
  take p;
  thus thesis by A5;
end;
