Fourth in the CDK Literature series. Really, a follow up on #3 which I wanted to get out, even though not really finished yet. But, after 3 comes 4, not 3b. Maybe 3.1, but that suggests at least 3.2-3.9 too, let alone full R (that was supposed to the space of all reals…) I’ll stick to positive non-zero integers. #1 and #2 are still available too.