reserve i,j,k,n for Nat;
reserve D for non empty set,
  p for Element of D,
  f,g for FinSequence of D;

theorem Th43:
  p in rng f & i in Seg(p..f) implies (f-:p)/.i = f/.i
proof
  assume that
A1: p in rng f and
A2: i in Seg(p..f);
  p..f in dom f by A1,FINSEQ_4:20;
  hence thesis by A2,FINSEQ_4:71;
end;
