??so .... ??consider... ??subfunctors of "[N^2,-]" : _comm monoid_ -> _set_ such as "{(x,y)|x^3=y^5}" ... and so forth ... if that makes any sense ... ???something about idea that such a sub-functor "can't participate in any reasonable cover" ... or something like that ... ??something about trying to formalize this idea ... ??? ... and so forth ... ???...