Theorem of the cube Theorem of the cube In mathematics, the theorem of the cube is a condition for a line bundle over a product of three complete varieties to be trivial. It was a principle discovered, in the context of linear equivalence, by the Italian school of algebraic geometry. The final version of the theorem of the cube was first published by , who credited it to André Weil. A discussion of the history has been given by . A treatment by means of sheaf cohomology, and description in terms of the Picard functor, was given by . The theorem states that for
Cube root or the other of the two complex cube roots of 1. For complex numbers, the principal cube root is usually defined as the cube root that has the greatest real part, or, equivalently, the cube root whose argument has the least absolute value. It is related to the principal value of the natural logarithm by the formula If we write "x" as where "r" is a non-negative real number and "θ" lies in the range then the principal complex cube root is This means that in polar coordinates, we are taking the cube root of the radius and dividing the