reserve f for Function;
reserve p,q for FinSequence;
reserve A,B,C for set,x,x1,x2,y,z for object;
reserve k,l,m,n for Nat;
reserve a for Nat;
reserve D for non empty set;
reserve d,d1,d2,d3 for Element of D;

theorem Th25:
  p just_once_values x implies p <- x = x..p
proof
  assume
A1: p just_once_values x;
  then x in rng p by Th5;
  then x..p in dom p & p.(x..p) = x by Th19,Th20;
  hence thesis by A1,Def3;
end;
