Knot theory is one of the fields of topology that studies geometric objects called knots. There are a lot of knots that exist
around us, such as bow-knots and half-knots. By studying this field, it is possible to mathematically classify whether knots
are the same. Since knot theory is a theoretical study, it plays an important role in theoretically building the foundation
of society. Regarding application to materials of knots, it has become possible to create a polymer compound having a structure
of a knot, and further, a material having a structure of knots called a fiber reinforced plastic material has been developed.
In this subject, we study properties of knots using knot invariants.