He always keeps in mind the phrase 'If one learns without thinking, it is a waste.'

A positive-semidefinite matrix is one of the important concepts in linear algebra.

He is studying the shape of a tetrahemihexahedron.

The semispinalis capitis muscle is a part of the neck muscles, helping to tilt the head backwards.

He injured his semitendinosus muscle.

He injured his semimembranosus muscle.

The semispinalis thoracis muscle is a deep muscle in the back that supports movement from the neck to the waist.

The semispinalis cervicis muscle is a part of the neck muscles, helping to pull the head back.

This model of the cubohemioctahedron is very beautiful, isn't it?

This 立方半八面體 is one of the shapes in geometry.