23.9 We said that 3

e, x e E Sleep(John, Past) A Name(x) = John was a plausible interpretation for "John slept." But it is not quite right, because it blurs the distinction between "John slept"

and "Some person named John slept." The point is that the former sentence presupposes that speaker and hearer agree on which John is being talked about. Write grammar and lexical rules that will distinguish the two examples.