reserve p,q,r for FinSequence;
reserve u,v,x,y,y1,y2,z for object, A,D,X,Y for set;
reserve i,j,k,l,m,n for Nat;

theorem Th98:
  p is one-to-one & rng p = {x,y,z} & <* x,y,z *> is one-to-one
  implies len p = 3
proof
A1: len <* x,y,z *> = 3 by FINSEQ_1:45;
  rng <* x,y,z *> = {x,y,z} by FINSEQ_2:128;
  hence thesis by A1,FINSEQ_1:48;
end;
