Not signed in (Sign In)

Start a new discussion

Not signed in

Want to take part in these discussions? Sign in if you have an account, or apply for one below

  • Sign in using OpenID

Site Tag Cloud

2-categories 2-category 2-category-theory abelian-categories adjoint algebra algebraic algebraic-geometry algebraic-topology analysis analytic-geometry arithmetic arithmetic-geometry beauty bundles calculus categories category category-theory chern-weil-theory cohesion cohesive-homotopy-type-theory cohomology combinatorics complex-geometry computable-mathematics computer-science connection constructive constructive-mathematics cosmology deformation-theory descent diagrams differential differential-cohomology differential-equations differential-geometry differential-topology digraphs duality education elliptic-cohomology enriched fibration finite foundations functional-analysis functor galois-theory gauge-theory gebra geometric-quantization geometry graph graphs gravity grothendieck group-theory harmonic-analysis higher higher-algebra higher-category-theory higher-differential-geometry higher-geometry higher-lie-theory higher-topos-theory homological homological-algebra homotopy homotopy-theory homotopy-type-theory index-theory infinity integration integration-theory k-theory lie lie-theory limits linear linear-algebra locale localization logic manifolds mathematics measure-theory modal-logic model model-category-theory monad monoidal monoidal-category-theory morphism motives motivic-cohomology multicategories noncommutative noncommutative-geometry number-theory of operads operator operator-algebra order-theory pasting philosophy physics planar pro-object probability probability-theory quantization quantum quantum-field quantum-field-theory quantum-mechanics quantum-physics quantum-theory question representation representation-theory riemannian-geometry scheme schemes set set-theory sheaf simplicial space spin-geometry stable-homotopy-theory stack string-theory subobject superalgebra supergeometry svg symplectic-geometry synthetic-differential-geometry terminology theory topology topos topos-theory type type-theory universal variational-calculus

Vanilla 1.1.10 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to nForum
If you want to take part in these discussions either sign in now (if you have an account), apply for one now (if you don't).
    • CommentRowNumber1.
    • CommentAuthorHarry Gindi
    • CommentTimeMay 9th 2010
    • (edited May 9th 2010)

    I dropped a query box over at Hurewicz fibration about a small difference of definition between the Lab and May's Concise Topology (in May, one only needs to have the RLP with respect to inclusions of CGWH spaces (into their cylinder objects at 0), while on the Lab, it says it must hold for all topological spaces.

    By the way, I like that page a lot, since it doesn't have an excessively long idea section (actually, there isn't any idea section, but I like that). It's written so it's easy to find the definition without wading through all of the clutter.

    I was wondering if it would be possible to swap the idea section and definition section around in a few articles and see if it makes them more readable. There's nothing more irritating than skipping the idea section only to find that the definition references the concepts introduced there. A definition should be readable entirely without having to read the idea section.

    • CommentRowNumber2.
    • CommentAuthorMike Shulman
    • CommentTimeMay 9th 2010

    I presume that “CGWH” means “compactly generated weak Hausdorff,” but it would have been better to say that. I believe the two definitions are actually different, although I don’t have an example to hand. Really, cofibrations and fibrations are defined by reference to any ambient topologically enriched category, which implies that the same map could be a co/fibration in one category but not in another larger or smaller one. I do have an example in the dual situation: all cofibrations in the category of compactly generated (weak Hausdorff) spaces are closed subspaces, but this is false for cofibrations in the category of all spaces, or even for merely compactly generated spaces (“k-spaces”).

    When I have time I’ll edit the entry some to this effect.

    • CommentRowNumber3.
    • CommentAuthorTodd_Trimble
    • CommentTimeMay 9th 2010

    I was wondering if it would be possible to swap the idea section and definition section around in a few articles and see if it makes them more readable.

    These things need to be looked at on a case-by-case basis. Why don’t you name the articles specifically, so we can have a look?

    A definition should be readable entirely without having to read the idea section.

    I am inclined to agree.

    • CommentRowNumber4.
    • CommentAuthorzskoda
    • CommentTimeMay 11th 2010

    I agree with Toby, each article has its own logic and difficulties and having rules to how to organize some article in general is counterproductive. Each article could have its own pedagogical organization according to the feeling of its creators.

    As you see I am back from the conference, but I returned back ssomehow sick (in unusual way, I still do not know if it is serious) and not in the shape to normally contribute yet.

    • CommentRowNumber5.
    • CommentAuthorMike Shulman
    • CommentTimeJan 8th 2019

    Mentioned the mixed model structure and the relation to Serre fibrations.

    diff, v27, current

Add your comments
  • Please log in or leave your comment as a "guest post". If commenting as a "guest", please include your name in the message as a courtesy. Note: only certain categories allow guest posts.
  • To produce a hyperlink to an nLab entry, simply put double square brackets around its name, e.g. [[category]]. To use (La)TeX mathematics in your post, make sure Markdown+Itex is selected below and put your mathematics between dollar signs as usual. Only a subset of the usual TeX math commands are accepted: see here for a list.

  • (Help)