YUJI ODAKA
A. For any degenerating Calabi-Yau family, we introduce new limit space which we call galaxy, whose dense subspace is the disjoint union of countably infinite open Calabi-Yau varieties, parametrized by the rational points of the Kontsevich-Soibelman's essential skeleton, while dominated by the Huber adification over the Puiseux series field.Other topics include: projective limits of toroidal compactifications ( §3), locally modelled on limit toric varieties ( §2.4), the way to attach tropicalized family to given Calabi-Yau family ( §4), which are weakly related to each other.Here, B denotes the essential skeleton (as 1.2 again) and B(Q) means its rational points with respect to the Q-affine structure, which does not depend on i by Theorem 2.1 (iii) and, where NKLT stands for the non-klt closed loci.Contents of §3 (Limit toroidal compactifications). In §3 over k = C in turn, we discuss on the projective limit of toroidal compactifications of [AMRT] and its analogue for more general (moduli) varieties. It sounds somewhat independent from §2 but here we observe an analogous phenomenon of the above theorem 1.2, especially the natural continuous maps to their tropical versions.More precisely, what we do there is as follows. Fix a locally Hermitian symmetric space M of non-compact type, i.e., of the ubiquitous form M = Γ\G/K where G is a real valued points of a simple algebraic group over Q, K its maximal compact subgroup with one dimensional center, Γ an arithmetic discrete subgroup of G. Some renowned examples are the moduli space of g-dimensional principally polarized abelian varieties or that of primitively polarized K3 surfaces with possibly ADE singularities (of fixed genera).Recall that for certain combinatorial data i.e., admissible collection of fans Σ = {Σ(F)}, there is an associate toroidal compactification M tor,Σ of M constructed in[AMRT], and its complex analytification M tor,Σ,an . Now, we consider and introduce the projective limit of all of its toroidal compactifications as a locally ringed space and call the limit toroidal compactification: M tor,∞ an := lim ← − Σ