>>551
つづき

By contrast, the links that occur in inter-universal Teichm¨uller
theory are constructed by partially dismantling the ring structures of the rings in their
domains and codomains [cf. the discussion of §2.7, (vii)], hence necessarily result in
much more complicated relationships between the universes ? i.e., between the labelling apparatuses for sets ? that are adopted in the Galois categories that occur in the domains and codomains of these links, i.e., relationships that do not respect the various labelling apparatuses for sets that arise
from correspondences between the Galois groups that appear and the respective
ring/scheme theories that occur in the domains and codomains of the links.

That is to say, it is precisely this sort of situation that is referred to by the term
“inter-universal”. Put another way,
a change of universe may be thought of [cf. the discussion of §2.7, (i)] as
a sort of abstract/combinatorial/arithmetic version of the classical notion
of a “change of coordinates”.
In this context, it is perhaps of interest to observe that, from a purely classical point of
view, the notion of a [physical] “universe” was typically visualized as a copy of Euclidean
three-space. Thus, from this classical point of view,

Ｐ29
a “change of universe” literally corresponds to a “classical change of the coordinate system ? i.e., the labelling apparatus ? applied to label points in
Euclidean three-space”!
Indeed, from an even more elementary point of view, perhaps the simplest example of the
essential phenomenon under consideration here is the following purely combinatorial
phenomenon: Consider the string of symbols
010
? i.e., where “0” and “1” are to be understood as formal symbols.

つづく