Inter-universal Teichmuller Theory I: Construction of Hodge Theaters
Inter-universal Teichmuller Theory I: Construction of Hodge Theaters
Inter-universal Teichmuller Theory I: Construction of Hodge Theaters
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INTER-UNIVERSAL TEICHMÜLLER THEORY I 73<br />
with “†” replaced by “□” to denote the various objects associated to the Θ-<strong>Hodge</strong><br />
theater labeled by “□”.<br />
Remark 3.6.2. If † HT Θ and ‡ HT Θ are Θ-<strong>Hodge</strong> theaters, then there is an<br />
evident notion <strong>of</strong> isomorphism <strong>of</strong> Θ-<strong>Hodge</strong> theaters † HT Θ ∼<br />
→ ‡ HT Θ [cf. Remark<br />
3.5.2]. We leave the routine details to the interested reader.<br />
Corollary 3.7. (Θ-Links Between Θ-<strong>Hodge</strong> <strong>Theaters</strong>) Fix a collection <strong>of</strong><br />
initial Θ-data (F/F, X F , l, C K , V, V bad<br />
mod<br />
, ɛ) as in Definition 3.1. Let<br />
† HT Θ =({ † F v<br />
} v∈V , † F ⊩ mod);<br />
‡ HT Θ =({ ‡ F v<br />
} v∈V , ‡ F ⊩ mod)<br />
be Θ-<strong>Hodge</strong> theaters [relative to the given initial Θ-data]. Then:<br />
(i) (Θ-Link) The full poly-isomorphism [cf. §0] between collections <strong>of</strong> data<br />
[cf. Remark 3.5.2]<br />
† F ⊩ ∼<br />
tht → ‡ F ⊩ mod<br />
is nonempty [cf. Remark 3.7.1 below]. We shall refer to this full poly-isomorphism<br />
as the Θ-link<br />
† HT Θ Θ<br />
−→<br />
‡ HT Θ<br />
from † HT Θ to ‡ HT Θ .<br />
(ii) (Preservation <strong>of</strong> “D ⊢ ”) Let v ∈ V. Recall the tautological isomorphisms<br />
□ Dv<br />
⊢ ∼<br />
→ □ Dv<br />
Θ for □ = †, ‡ — i.e., which arise from the definitions when<br />
v ∈ V good , and which arise from a natural product functor [cf. Example 3.2, (v)]<br />
when v ∈ V bad . Then we obtain isomorphisms<br />
† D ⊢ v<br />
∼<br />
→ † D Θ v<br />
∼<br />
→ ‡ D ⊢ v<br />
by composing the tautological isomorphism just mentioned with any isomorphism<br />
induced by a Θ-link isomorphism as in (i).<br />
(iii) (Preservation <strong>of</strong> “O × ”) Let v ∈ V. Recall the tautological isomorphisms<br />
O ×□ ∼<br />
→O ×□ [where we omit the notation “(−)”] for □ = †, ‡ — i.e.,<br />
Cv<br />
⊢ Cv<br />
Θ<br />
which arise from the definitions when v ∈ V good [cf. Examples 3.3, (ii); 3.4, (iii)],<br />
and which are induced by the natural product functor [cf. Example 3.2, (v)] when<br />
v ∈ V bad . Then, relative to the corresponding composite isomorphism <strong>of</strong> (ii), we<br />
obtain a composite isomorphism<br />
O × † C ⊢ v<br />
∼<br />
→ O × † C Θ v<br />
∼<br />
→ O × ‡ C ⊢ v<br />
by composing the tautological isomorphism just mentioned with any isomorphism<br />
induced by a Θ-link isomorphism as in (i).<br />
Pro<strong>of</strong>. The various assertions <strong>of</strong> Corollary 3.7 follow immediately from the definitions<br />
and the discussion <strong>of</strong> Examples 3.2, 3.3, 3.4, and 3.5. ○