He is writing a paper on coding theory.

String theory is a branch of physics that is a theory for understanding the basic structure of the universe.

He wrote a new paper on string theory.

He is particularly interested in string theory in physics.

He understands the importance of learning.

He is majoring in psychology.

Gaku is my best friend.

He has a deep interest in archaeology.

I am majoring in linguistics at university.

He is interested in the study of constructed languages.