(algebra) additivity

be based on

(arithmetic) addition

Principle. / A fundamental truth that bases on. / An eternal law that is common over lots of fact. / (philosophy) A basic fact which explains why something exists.

mathematics (field of study)

sex, gender / (grammar) gender

question, problem on homework etc. / a question; a matter (of time etc.) / a problem (something that needs to be dealt with); a trouble / an issue; a matter

(religion) fundamentalism

(mathematics) pure mathematics

applied mathematics