👉 A cothurnian is a type of mathematical function in which the input and output are both rational numbers. This means that the domain and range of a cothurnian function can be written as: f(x) = (1/2)(x^3 - 3x + 2) where x is an irrational number, and 0 < x < 1. A cothurnian function has both positive and negative values. The domain of a cothurnian function
