Which of the following principles is NOT part of the three kata principles?

The principle that is not part of the three kata principles is up/down. The three kata principles include the contrasts of fast/slow, light/heavy, and expansion/contraction, which are crucial for understanding the dynamics and execution of kata in martial arts.

Fast/slow refers to the varying speeds at which movements can be executed, emphasizing timing and control in techniques. Light/heavy focuses on utilizing the right amount of force, either light for finesse or heavy for power, depending on the situation. Expansion/contraction deals with the flow of energy, indicating how movements can either spread out or tighten in focus during a kata.

Up/down, while it might relate to movement direction in martial arts, is not one of the foundational principles that govern the practice and understanding of kata. Hence, it does not fit within the established framework of the three primary kata principles.