Which work does James Joyce use as a focus and model for his modern novel entitled Ulysses?

Oedipus Rex, a tragedy by Sophocles, focuses on themes of fate, free will, and tragic downfall. While it is a significant work in the canon of Greek literature, it does not share the structural or thematic elements that Joyce employed in Ulysses. Joyce's novel is more directly aligned with a journey and the intricacies of daily life, which Oedipus does not represent.

Siddhartha, by Hermann Hesse, is a philosophical novel exploring the journey of self-discovery and spiritual enlightenment. Though it offers rich themes of personal growth, it lacks the narrative structure and mythological framework that Joyce adapted from The Odyssey. Therefore, it does not serve as a model for Ulysses.

Paradise Lost, an epic poem by John Milton, deals with themes of sin, redemption, and the fall of man. While it is a significant literary work, its themes and structure do not align with the modernist approach or the specific narrative parallels that Joyce sought to establish with The Odyssey.

Antigone, another classic Greek tragedy by Sophocles, revolves around themes of moral conflict and familial loyalty. While it is a profound exploration of duty and ethics, it does not provide the narrative framework or character parallels that Ulysses derives from The Odyssey.