theorem Th8:
  m+n<len p implies (p/^n).m = p.(m+n)
proof
  assume
A1: m+n<len p;
  then
A2: m<len p-n by XREAL_1:20;
  len (p/^n)=len p-n by A1,Th7,NAT_1:12;
  hence thesis by Def2,A2,AFINSQ_1:86;
end;
