Talk:Ideal class group

message: To what group of people is this article targeted? At first glance, having noticed the section "technical development" later on, I thought that the article must give an easy introduction followed by this "technical development". Nevertheless, it seems that one must know quite a few concepts to understand the (first sentence of the) lead alone. Was this intended, or was it intended that even laypeople should understand this article? --PST 08:20, 21 September 2009 (UTC)
thread_title:  Technical development 

message: Shouldn't there be a discussion of the class number that appears in the binary quadratic from page http://en.wikipedia.org/wiki/Binary_quadratic_form and the class number in the ideal class number page. I came to Wikipedia to find out the connection, but no luck. Sorry, this is my first talk contribution, so maybe it should be formatted differently
Bergv (talk) 01:48, 19 October 2009 (UTC)
replies: text: The narrow class group of a quadratic order (i.e. a ring in a quadratic field) of discriminant D is the same as the class group of the equivalence classes of binary quadratic forms of discriminant D under Gauss composition (as described here for example). It would be nice to have a mention here. RobHar (talk) 04:44, 19 October 2009 (UTC)

text: I've updated the article. RobHar (talk) 07:10, 12 June 2010 (UTC)
thread_title:  Relation ideal class group with binary quadratic forms 

message: In the introduction, the ideal class group is defined as "the quotient group JK/PK where JK is the whole fractional ideals of K and PK is the principal ideals of K." What is meant by the quotient with the many ideals and not with a single object? I think this point should be clarified. K9re11 (talk) 13:32, 11 March 2015 (UTC)
thread_title:  Definition 

message: In the first sentence: "for a field K an ideal class group" Surely this should refer to an integral domain, rather than a field. Fields have only the two trivial ideals, the zero ideal and the entire field. It also is inconsistent with the definition section.  — Preceding unsigned comment added by 2601:142:1:8B70:A288:B4FF:FE41:1410 (talk) 01:38, 3 March 2017 (UTC)
replies: text: The phrase "for a field K, an ideal class group is ..." is correct if K is an algebraic number field. Nevertheless, I agree that the formulation was confusing and formally incorrect. I have fixed this. D.Lazard (talk) 09:17, 3 March 2017 (UTC)
thread_title:  First sentence 

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thread_title:  External links modified