Charts Definition and 54 Threads

4 charts seem to cover it. BUt only 2 will do for a minimal number? Just like 2 charts will do to cover a sphere? Even though there are 6 all together.

Hey guys, does anyone uses or knows about a software package that allows me to do gradation charts? (a gradation chart is a simple graphic where the x-axis is in logarithmic scale and the y-axis is in natural scale)

I was wondering about this, I've never seen any general theorem. Obviously it takes more than one, but I would think that in general it can take quite a few, for I can't see how to cover a torus with only 2. Is there any sort of general result on this?

anything out there that could help me with this? or is there no limit? or does it depend on gauge?