Is this formalization correct, and if it's not, why? And what would be the correct formalization? I am assuming Russell's theory of definite descriptions.
The author of The Da Vinci Code is the author of Angels and Demons
$$\exists x(P(x) \wedge Q(x) \wedge \forall y((P(y) \vee Q(y)) \supset x = y))$$ ($P$ = author of The Da Vinci Code, $Q$ = author of Angels and Demons)
Your symbolization is correct, but the following symbolization is a little more explicit about the two authors being one and the same:
$$\exists x \exists y (P(x) \land \forall z (P(z) \rightarrow z = x) \land Q(y) \land \forall z (Q(z) \rightarrow z = y) \land x = y)$$
So in here, I first make $x$ the one and only author of The Da Vinci Code, and $y$ the one and only author of Angels and Demons, and finally I state that they are identical. Your symbolization turns out to be logically equivalent to this, but I think the meaning of the original English sentence is a little more hidden in yours and a little more explicit in this one.
