Number theory is a branch of mathematics that primarily studies the properties of integers.

Epistemology is the philosophical study of the origin, nature, and scope of knowledge.

He strongly supports royalism.

He is an expert in semiotics, and his theories are very profound.

He is an expert in ring theory and has written many papers in the field.

He is majoring in semantics at university.

He is deepening his research on eschatology.

He was a fatalist, believing that all events are determined by fate.

He strongly advocated the hokushin theory.

He strongly advocated the theory of southward advancement.