What sequence of events did Aristotle lay out for the structure of the Greek tragedy?

As set out by Aristotle in his Poetics in 350 B.C., tragedy generally follows a set sequence of events. First, the hamartia takes place. This is the tragic error committed by the hero, and it usually is committed unwittingly. Oedipus' act of killing Laius and marrying Jocasta is the hamartia in Oedipus the King. The unexpected turn of events that brings this error to light is known as the peripeteia, and the hero's recognition of this error is the anagnorisis. According to Aristotle, the peripeteia and the anagnorisis are most effective when occurring at the same time. They often come about when the true identity of one of the characters becomes known. This is the case for Oedipus, whose discovery of who his real father is causes him to recognize that his wife is his mother, thereby leading to the reversal of his situation from happiness to misery. Lastly comes the catharsis, the release of the emotions of fear and pity that the tragedy has aroused in the audience.