His explanation was impossible to understand.

He is passionate about competitive programming.

He used himself as a reflexive pronoun.

Understanding the algorithm of the regression tree is difficult.

Reflexive verbs are used to express actions where the subject is acting on itself.

Using tail recursion can sometimes improve the performance of a program.

This program has recursivity.

This problem can be solved with a recursive approach.

Object-oriented programming is an important method for improving the efficiency of software development.

Natural language understanding is an important field of artificial intelligence.