public Instantiation findOwner(final int i) {
			if (!subroutine.ownsInstruction(i)) {
				return null;
			}
			if (!dualCitizens.get(i)) {
				return this;
			}
			Instantiation own = this;
			for (Instantiation p = previous; p != null; p = p.previous) {
				if (p.subroutine.ownsInstruction(i)) {
					own = p;
				}
			}
			return own;
		}