>>250
なるほど、言いたいことが少し分かってきた

　>>92 より Z＾関連で、前スレ https://rio2016.5ch.net/test/read.cgi/math/1623019011/930 より MITの講義
https://math.mit.edu/classes/18.782/lectures.html
LECTURES MIT Arithmetic Geometry
https://math.mit.edu/classes/18.782/LectureNotes4.pdf
Introduction to Arithmetic Geometry Fall 2013
Lecture #4 Andrew V. Sutherland
4.2 The ring of p-adic integers
Definition 4.3. For a prime p, the ring of p-adic integers Zp is the inverse limit
Zp = lim ←- Z/p^nZ
of the inverse system of rings (Z/p^nZ) with morphisms (fn) given by reduction modulo pn
(for a residue class x ∈ Z/pn+1Z, pick an integer x ∈ x and take its residue class in Z/p^nZ).
The multiplicative identity in Zp is 1 = (￣1, ￣1, ￣1, . . .), where the nth ￣1 denotes the residue class of 1 in Z/p^nZ.
Example 4.4. If we represent elements of Z/p^nZ by integers in [0, pn - 1], in Z_7 we have
2 = (2, 2, 2, 2, 2, . . .)
2002 = (0, 42, 287, 2002, 2002, . . .)
Example 4.7. We have the following p-adic expansion in Z_7:
2 = (2, 0, 0, 0, 0, 0, 0, 0, 0, 0, . . .)
2002 = (0, 6, 5, 5, 0, 0, 0, 0, 0, 0, . . .)
(引用終り)

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