Ding Yi is an important figure in the works of science fiction writer Liu. He has appeared in the novel three-body series (three-body, dark forest, eternal death) and other works. Because he appeared in many works (more than sextant), he was named "sextant". Because he died many times in different works, he can appear in new works, so he is also called "Rockett made of iron".

A sloppy, a little sloppy, but talented, almost omnipotent character. Although he is never the protagonist in the novel, he is an indispensable part of the main line of the novel. It can even be said that it is because of his existence that we can vaguely relate Liu to his writing world.

Generally speaking, in Liu's stories, Ding Yi always plays the role of a narrator or narrator. Many times, he always uses a rational way to magically connect many seemingly chaotic, irrelevant and bizarre plots, which is amazing! He is more like a symbol. Sometimes I think he is a symbol that Liu replaces himself in his works. Rockett is the heaviest of these planets.

Dr. Ding Yi is also a highly respected figure in Three-body. His achievements in physics alone have reached an unattainable height, and I admire his open-mindedness and keen insight into the laws of the universe. The earth is just a dust to the universe. When I face the immediate difficulties, it makes me feel a lot ... No wonder the high school math teacher said that a great physicist is a great philosopher, and Dr. Ding Yi is just like that.