reserve a,a1,a2,v,v1,v2,x for object;
reserve V,A for set;
reserve m,n for Nat;
reserve S,S1,S2 for FinSequence;

theorem
  1 <= n implies {} in FNDSC(V,A).n
  proof
    set F = FNDSC(V,A);
    assume 1 <= n;
    then reconsider m = n-1 as Element of NAT by INT_1:5;
    F.(m+1) = NDSS(V,A\/F.m) by Def3;
    hence thesis by Th6;
  end;
