Talk:Ringed space

message: I removed the paragraph
:One can trace this back to the logical form of the definition of local ring. In a clean logical formulation, it can be put as 'for all r in R, either there is s with sr = 1 or t with t(1-r) = 1'. In topos theory it is shown how the theory therefore qualifies for a classifying topos, which parametrises local rings. The structure of a locally ringed space is equivalent to the right kind of morphism to this topos - which can also be identified via algebraic geometry.
While the classifying topos sentence is clear, I cannot make sense of the last sentence. A morphism to the classifying topos from where? From the topological space X considered as category? The word "which" in the last sentence: does it refer to "right kind of morphism" or to "morphism" or to "this topos"? How does algebraic geometry identify this? AxelBoldt 16:56, 13 Nov 2003 (UTC)

message: It is unclear to me why the definition of Ringed Spaces is necessary.  As stated, it is just a sheaf of rings.  The only way I can see out of this conundrun is if the definition of morphism between ringed spaces is a particular type of the possible ways to define a morphism between sheaves.  Hence, when somebody tells me that "X is a ringed space" then I will take it for a short word to X being a sheaf of rings where we consider a particular type of morphism between then.  
I am aware that one could say that a ringed space is not a sheaf of rings since it is a pair (M,F) where M is a topological space and F is a sheaf of rings over M.  However, M is already an information we can get out of F.  Therefore, it seems to me redundant to say that we have such a pair (M,F) to just saying that we have an F.
Just to be more precise.  To me to say that we have a ringed space means that we have an object of a very specific category.  What makes this category special is not its objects, but the set of morphisms we allow between any two objects.
17:23, 16 January 2008 (UTC)
replies: text: (1) The definition of a ringed space is unnecessary (since it is nothing but a sheaf of rings; hopefully the new lead makes this clearer). (2) The article on a ringed space is not necessarily unnecessary, for the reason already mentioned. -- Taku (talk) 01:32, 15 January 2019 (UTC)
thread_title:  Definition 

message: The first sentence of the article contains this passage:
"a topological space together with a collection of commutative rings, the elements of which are "functions" on each open set of the space."
If "functions" means functions, I would hope the article would say that — without quotation marks.
If it means something else, and in any case, nobody has the vaguest idea of what "functions" means. So let's use words that users of Wikipedia actually understand.  I hope someone knowledgeable on this subject will improve the wording.
Do not ask readers to suspend their comprehension of the first sentence until they read further into the article or sentence. The first sentence and paragraph, more than any other, should be crystal-clear.2600:1700:E1C0:F340:ACC6:71D3:942:222D (talk) 04:00, 7 January 2019 (UTC)
replies: text: The tension here is whether to be precise or to be understandable in the first paragraph. To answer your question, a ringed space is an abstract concept and it itself involves no concrete objects like "functions"; but the idea is that one wants to think elements in the rings attached to a space to be "functions". "Functions" here are metaphors; like a desktop (computing) in an operating system, which itself involves no physical desk. Anyway, the current lead is not great if not problematic; so I will give a shot (editing it). -- Taku (talk) 00:55, 15 January 2019 (UTC)
thread_title:  It is not a good idea to use words that require quotation marks 

message: We need to give such an example. -- Taku (talk) 01:28, 15 January 2019 (UTC)
thread_title:  A ringed space that is not a locally ringed space