A : What is your major?
B : Not theory.
A : Do you mean it is experimental?
B : No, it is theoretical.
A : What kind of theory?
B : Not theory.
A : Don't you major in theory?
B : Yes, I major in theory.
A : What kind of theory?
B : Not theory.
A : Not theory?
B : Yes. My major is "knot" theory.
　B はこの日のために knot theory を専攻してきたに違いない。