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Jun 25, 2017 at 10:31 history edited Myshkin CC BY-SA 3.0
+ top level tag (nt.) + ref. req.
Nov 3, 2012 at 13:15 vote accept Keenan Kidwell
Nov 3, 2012 at 8:37 comment added Olivier No examples are given, but from his description of the general construction and say the content of Weber Algebra, you get the anticyclotomic extension for free.
Nov 3, 2012 at 8:34 comment added Olivier I think the idea of $\mathbb Z_{p}$-extension is the kind of idea that have been around at least implicitly for a long time. Certainly Kronecker and Weber knew explicit descriptions of abelian extensions of CM fields, and from that knowledge, introducing the $\mathbb Z_{p}$-extension is just singling out some particularly interesting extensions. I think that Iwasawa is probably the person who first explicitly introduced them. Already in his 1959 article, the general set-up is in place and a general construction of $\mathbb Z_{p}$-extension is given using class field theory.
Nov 3, 2012 at 5:47 comment added Filippo Alberto Edoardo ...I would say it is the most obvious example beside cyclotomic one, so I guess Iwasawa himself must have thought about it especially when looking for extensions with non-trivial invariants.
Nov 3, 2012 at 5:46 comment added Filippo Alberto Edoardo I do not really know here it first appears, but I think you should have a look at the 1973 paper by Iwasawa "On the $\mu$ invariants in $\mathbb{Z}_\ell$-extensions". Note that for imaginary quadratic fields, Leopoldt conjecture is almost obvious, as it is for $\mathbb{Q}$, because there are no global units beside roots of units, so it was a standard fact that the compositum of all $\mathbb{Z}_p$-extensions of an imaginary quadratic field K has Galois group $\mathbb{Z}_p^2$, on which $\mathrm{Gal}(K/\mathbb{Q})$ acts, and identifies the anticyclotomic extension as −1-eigenspace...
Nov 3, 2012 at 3:46 answer added Yuri Zarhin timeline score: 6
Nov 3, 2012 at 0:28 history asked Keenan Kidwell CC BY-SA 3.0