I am writing an essay explaining the tragic irony in Oedipus Rex. Ideas please?

In the discussion of the tragic irony of Oedipus
Rex, the writer may find that it is worthwhile to direct the reader toward the
tremendous impact that this irony has upon the character of the King of Thebes, Oedipus. That is,
the writer may wish to provide the reader with an explanation of how it is that the situational
and dramatic irony of Sophocles's Oedipus Rex effect the tragic
ending.

So, if the writer takes this direction of explaining how the
various ironies effect the tragedy of Oedipus, the focus of the paper will be upon defining the
situational irony and the dramatic irony and the examples thereof that she uses to support the
thesis of the force of this irony. For instance, the moment of what Aristotle calls the
"reversal" itself is ironic. When the messenger comes to tell Oedipus of the death of Polybos,
whom he thinks is the father of Oedipus, the situational irony effects this reversal. For,
Oedipus learns from the messenger inadvertently that Polybos is not, in fact his father. And this
ironic moment for the messenger produces the opposite effect of what the messenger has
anticipated. Of course, the greatest irony is the dramatic irony of Oedipus's declaration that he
will save Thebes when, in fact, he is the cause of the plague. Thus, by tracing the effects of
the various incidences of irony, the writer can demonstrate how it is this very irony that
propels the play Oedipus Rex to its tragic conclusion.