👉 The term "quadriciliate" is a technical term used in mathematics and engineering to describe a function that has a singularity at one point, but its derivative does not have any singularities at this point. This property is often used in optimization problems where the gradient of the objective function is known to be non-singular at the point of interest. In mathematical terms, a quadriciliate is an object that satisfies the following condition: $$\nabla f(x) \cdot (x