This is a book, most of all, about reading I believe; and for the writer, a book about how a book is read should be of utmost value. Know thine enemy. Know your audience.
Back in reader mode of Chapter 3, we see another element of writing/reading as focus; that of reader experience brought to the reading which in effect changes what is read.Calvino also touches here on relevance and necessary grounding to make a reader interested in what is being read.
And he seems to mean "or Ludmilla?" But he doesn’t finish the sentence; and to be sincere you should answer that you can no longer distinguish your interest in the Cimmerian novel from your interest in the Other Reader of that novel. (p. 51)
While this simply defines your interest in the girl, the Other Reader, now given the name Ludmilla, as you explain your purpose in coming to meet a professor who is an expert on Cimmerian literature, it does to me reflect the notion of reality/fiction bonding in areas of similarity borne of experience. Here it becomes a bit clearer:
Now, moreover, the professor’s reactions at the name Ludmilla, coming after Irnerio’s confidences, cast mysterious flashes of light, create about the Other Reader an apprehensive curiosity not unlike that which binds you to Zwida Ozkart, in the novel whose continuation you are hunting for, and also to Madame Marne in the novel you had begun to read the day before and have temporarily put aside, and here you are in pursuit of all these shadows together, those of the imagination and those of life. (p. 51)