(1) Oedipus knows his wife is Jocasta.(2) Jocasta is Oedipus's mother.
(3) Does Oedipus know his wife is his mother?
(4) No. If the diagram explicitly represents all the knowledge in the universe of discourse, there is no arrow [Oedipus knows (Jocasta mother-of Oedipus)].
For a presentation of SVO diagrams please refer to Representation of Symbolic Knowledge