reserve i,j,k,n,l for Element of NAT,
  K for Field,
  a,b,c for Element of K,
  p ,q for FinSequence of K,
  M1,M2,M3 for Matrix of n,K;
reserve D for non empty set,
  t for FinSequence of D,
  A for Matrix of n,D;

theorem
  M1 is anti-circular & M2 is anti-circular implies M1-M2 is anti-circular
proof
  assume that
A1: M1 is anti-circular and
A2: M2 is anti-circular;
  -M2 is anti-circular by A2,Th55;
  hence thesis by A1,Th52;
end;
