I am not convinced since in this world you can have the following rects: 1 x 1 1 x -1 -1 x -1 Is just the middle one a cut out? I reckon you need the axiom

I am not convinced since in this world you can have the following rects: 1 x 1 1 x -1 -1 x -1 Is just the middle one a cut out? I reckon you need the axiom from the field to do generalize this to negative numbers. https://en.m.wikipedia.org/wiki/Field_(mathematics) https://en.m.wikipedia.org/wiki/Field_(mathematics)