Talk:Space group

message: How can I mark this page as 'needs to be clearer for a lay person'? Its good, but some of the english seems to be wrong, and not being an expert I am not able to fix it...
"with a threefold screw axis projecting on one face, and two fold rotation axis another."
Is this simply
"with a threefold screw axis projecting on one face, and two fold rotation axis on another."
?
It isn't clear where this information comes from given the space group.
--Dan|(talk) 17:15, 25 July 2005 (UTC)
replies: text: I fixed this. The 3 and 2 are in the notation, the subscript indicates that it is a screw axis.--Patrick 10:33, 2 January 2006 (UTC)
thread_title: Accessibility for lay readers

message: I've brought back some old text and put it at the start of the article under the heading 'Space groups in crystallography'. All the text from the previous version is still there, but I've put it under the heading 'Group theory'. I don't propose keeping things exactly as they are now, but Patrick: what do you think of structuring the article along these lines? O. Prytz 07:48, 2 January 2006 (UTC)
replies: text: Ok.--Patrick 10:55, 2 January 2006 (UTC)
replies: text:  I would suggest forking off most of the text in "group theory" as mathematical treatment of space groups or something like that, leaving here a shorter, and more elementary version. I believe this is the only way of keeping all the text Patrick wrote, as it is really big, and it does not read as well as the much smaller first section. Oleg Alexandrov (talk) 16:47, 2 January 2006 (UTC)
replies: text:  And some text could go to screw axis. I believe we have enough material to write a nice article on that, where we can expand a bit beyond what is now in space group about screw axis. Oleg Alexandrov (talk) 16:50, 2 January 2006 (UTC)
replies: text:  I agree that the group theory text still 'dominates' the article a bit, but I'm not too worried. However, I agree that we should move the parts about screw axis and glide plane. O. Prytz 18:45, 2 January 2006 (UTC)

text: I think it is fine to move it over, then we can more easily check the differences. The example should link to Rhombohedral and we should explain how it fits in in that page. More examples would be better too.--Patrick 00:23, 5 January 2006 (UTC)
replies: text: Ok, I've changed the first section to my edited version. I haven't added the things you suggest yet, but I agree that more examples would be good. O. Prytz 11:17, 5 January 2006 (UTC)
thread_title: Made some changes

message: I've created the articles Screw axis and Glide plane using some of the text from this article. These articles are stubs and should be expanded somewhat so please go ahead. I hope they  don't need to get too mathematical, we should at least keep an introductory text at the level of the current text. 
As a follow up, I've removed the screw axis and glide plane paragraphs in the group theory section of this article. Hope that's ok. Patrick: would it be at all possible to shorten the group theory text any further, and instead refer to another article?O. Prytz 12:08, 8 January 2006 (UTC)
replies: text: I do not think that is needed, many artices are longer, and there is not a clear subtopic suitable for splitting off.--Patrick 00:28, 10 January 2006 (UTC)
thread_title: More changes

message: I removed the attention tag as I think the article has gotten a lot better. Some work is still needed though. What do you guys think? O. Prytz 07:28, 10 January 2006 (UTC)
replies: text: The article refers to Space group notation that is not fully explained, i.e. R and others.--Shakujo 04:31, 29 January 2007 (UTC)
thread_title: Removed attention tag

message: "A definitive source regarding 3-dimensional space groups is Hahn (2002)."
Is it appropriate to recommend a textbook in the lead? I haven't seen another article have such a line in its lead; it almost seems like an advertisement. Is there any objection to me removing it? JHobbs103 (talk) 22:03, 29 May 2010 (UTC)
replies: text: It is more a handbook than a textbook, really. Honestly, there is not much of a market for two compendia of all the spacegroups and their symmetries and whatnot, so I doubt that there is anything comparable (disclosure: I do not think I added that text, but that is the book I use). Certainly coming from the IUCR gives it a certain gravitas. I changed it to the title of the book, but I am not terribly wedded to keeping the mention if you think it really detracts from the article. - 2/0 (cont.) 00:42, 30 May 2010 (UTC)
thread_title:  Is the lead appropriate? 

message: I compiled a list of space groups with their full names, with spaces for readability, replacing redirect at list of space groups. Tom Ruen (talk) 23:17, 10 February 2014 (UTC)
thread_title:  Space group full names 

message: I think the introdution should change to
"
In mathematics and physics, a space group is the symmetry group of a configuration in space, usually in three dimensions. A symmetry group of R3 belongs to a space group  the subgroup of all translations in that group is generated by 3 linearly independent translations and the symmetry group has only finitely many cosets of the subgroup of all translations in it. Two symmetry groups that belong to a space group belong to the same space group iff there exists a linear transformation R such that the function that assigns to each transformation T in the first symmetry group R-1TR is a bijection from the first symmetry group to the second symmetry group. Note that R-1TR doesn't necessarily have to be an isometry for all isometries T; it just has to be an isometry for all symmetry operations T of the first symmetry group. In total there are 219 such symmetry groups. For each space group, either all structures that belong to that space group are chiral or none of them are. Some authors consider chiral copies of a space group to be distinct, that is, there define a space group pretty much the same way except for replacing the criterion "there exists a linear transformation R such that" with "there exists a non-inverting linear transformation R such that". 11 of the members of the first definition of a space group can be split into 2 members of the second definition leaving a total of 230 space groups according to the second definition. Those 11 space groups are called chiral space groups. Although all structures that belong to a chiral space group are chiral structures, not all chiral structures that belong to a space group belong to a chiral space group. Space groups are also studied in dimensions other than 3 where they are sometimes called Bieberbach groups, and are discrete cocompact  groups of isometries of an oriented Euclidean space.
In crystallography, space groups are also called the crystallographic or Fedorov groups, and represent a description of the symmetry of the crystal. A definitive source regarding 3-dimensional space groups is the International Tables for Crystallography ()."
to better explain what a space group is.
Can anyone find sources for any of the information I added? Blackbombchu (talk) 01:17, 24 November 2014 (UTC)
thread_title:  What is a space group? 

message: Comparing the definition of "group" in the context of this article to the mathematical definition of a group, the requirements of "space groups" are stated as properties of certain "group actions" of mathematical groups. For readers only familiar with the properties of a mathematical group, it would helpful to point out that term "group" in this article may often refer to what mathematicians call a "group action".  — Preceding unsigned comment added by Tashiro (talk • contribs) 15:55, 13 February 2015 (UTC)
thread_title: Group vs Group Action