>>77
つづき

https://www.kurims.kyoto-u.ac.jp/~motizuki/Inter-universal%20Teichmuller%20Theory%20IV.pdf
INTER-UNIVERSAL TEICHMULLER THEORY IV: ¨
LOG-VOLUME COMPUTATIONS AND
SET-THEORETIC FOUNDATIONS
Shinichi Mochizuki
April 2020
P6
Here, we recall in passing
that such “extensions of universe” are possible on account of an existence axiom
concerning universes, which is apparently attributed to the “Grothendieck school”
and, moreover, cannot, apparently, be obtained as a consequence of the conventional ZFC axioms of axiomatic set theory [cf. the discussion at the beginning of
§3 for more details].

P67
Section 3: Inter-universal Formalism: the Language of Species
We shall refer to such models as ZFC-models.
Recall that a (Grothendieck) universe V is a set satisfying the following axioms [cf.
[McLn], p. 194]:

The various ZFC-models that we work with may be thought of as [but are
not restricted to be!] the ZFC-models determined by various universes that are
sets relative to some ambient ZFC-model which, in addition to the standard axioms of ZFC set theory, satisfies the following existence axiom [attributed to the
“Grothendieck school” ? cf. the discussion of [McLn], p. 193]:

We shall refer to a ZFC-model that also satisfies this additional axiom of the
Grothendieck school as a ZFCG-model.

つづく