Notes for AKT-140324/0:51:37

Showing that the box coproduct respects the 4T relation.

Throughout, the tensor of two diagrams actually refers to a sum of all possible ways of placing the connected components of the sub-diagrams 1, 2, 3, and 4 on the left or right side of the tensor, in line with the definition of box. This leads to a cleaner presentation that conveys the same argument.