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-category 2-category-theory abelian-categories adjoint algebra algebraic algebraic-geometry algebraic-topology analysis analytic-geometry arithmetic arithmetic-geometry book bundles calculus categories category category-theory chern-weil-theory cohesion cohesive-homotopy-theory cohesive-homotopy-type-theory cohomology colimits combinatorics complex complex-geometry computable-mathematics computer-science constructive cosmology deformation-theory descent diagrams differential differential-cohomology differential-equations differential-geometry differential-topology digraphs duality elliptic-cohomology enriched fibration finite foundations functional-analysis functor gauge-theory gebra geometric-quantization geometry goodwillie-calculus graph graphs gravity grothendieck group 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 integration integration-theory k-theory kan lie lie-theory limits linear linear-algebra locale localization logic manifolds mathematics measure-theory modal-logic model model-category-theory monads monoidal monoidal-category-theory morphism motives motivic-cohomology nlab noncommutative noncommutative-geometry number-theory of operads operator operator-algebra order-theory pages pasting philosophy physics 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 science set set-theory sheaf simplicial space spin-geometry stable-homotopy-theory string string-theory 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.
    • CommentAuthorUrs
    • CommentTimeApr 12th 2011

    I have split off formally etale morphism from etale morphism. Then I added the general-abstract topos theoretic characterization, essentially by copy-and-pasting the discussion from formally smooth morphism (and replacing epimorphisms by isomorphisms)

    • CommentRowNumber2.
    • CommentAuthorDavidRoberts
    • CommentTimeApr 12th 2011

    Is equation (1) right at formally etale morphism? In that it has a \prod instead of a \coprod

    It just looks funny to me, in that you could have used × blah\times_{blah} instead.

    • CommentRowNumber3.
    • CommentAuthorUrs
    • CommentTimeApr 12th 2011
    • (edited Apr 12th 2011)

    it’s supposed to be the fiber product, yes. I thought the bigger the symbol for blahblah, the more reason to use blah\prod_{blah} instead of × blah\times_{blah}! :-)

    • CommentRowNumber4.
    • CommentAuthorDavidRoberts
    • CommentTimeApr 13th 2011

    I raised this TeX.SE question in order to pretty up the situation. Unfortunately, the maths I was trying to use didn’t work there, so here it is: $one \sideset{}{_{three}}\prod two$ (in source form, because it doesn’t work here either).

    • CommentRowNumber5.
    • CommentAuthorDavidRoberts
    • CommentTimeApr 13th 2011

    Hmm, how about nolimitsa\prod\nolimits{_a}

    no, that doesn’t work, at least here.

    • CommentRowNumber6.
    • CommentAuthorUrs
    • CommentTimeMar 19th 2012
    • (edited Mar 19th 2012)

    I have added in the References-section at formally etale morphism a mentioning of Joyal’s lectures from the 1970 where the pullback-definition discussed in the entry apparently first appears (is there any printed trace of these lectures?) and to an article by Dubuc where this is recalled / discussed.

    • CommentRowNumber7.
    • CommentAuthormaxsnew
    • CommentTimeAug 29th 2017
    • (edited Aug 29th 2017)
    This page had several links to that no longer seem to work.
    Maybe it's a holdover from previous years, but they were constructed using an explicit html <a> tag instead of the usual markup for cross-referencing on the nlab with double brackets.
    As a quick fix, I just replaced nlab.mathforge everywhere with ncatlab.

    I don't know if this is a known issue, but it worries me that there might be a lot of these bad links floating around (though I haven't encountered them) so I thought I should bring this to your attention.
    • CommentRowNumber8.
    • CommentAuthormaxsnew
    • CommentTimeAug 29th 2017
    Also as to the content of the page, I find the introduction very confusing. The page is about formally etale morphisms, but the first sentence is about formally etale spaces, making the 2nd sentence incongruous and I'm not quite sure how to fix it.
    • CommentRowNumber9.
    • CommentAuthorRodMcGuire
    • CommentTimeAug 29th 2017
    • (edited Aug 29th 2017)

    This page had several links to … they were constructed using an explicit html <a> tag instead of the usual markup for cross-referencing on the nlab with double brackets.

    I guess whoever made then didn’t know how to link to sections and HowTo#links_to_sections doesn’t help much and really needs to be updated.

    In particular one can just use “pipe” naming: [[HowTo#links_to_sections|linking sections]] -> linking sections.

    EDIT: I’m now working on updating HowTo#how_to_make_links_to_subsections_of_a_page

    • CommentRowNumber10.
    • CommentAuthorUrs
    • CommentTimeAug 29th 2017

    Thanks for the alert in #8. I don’t know what happened there. I have removed the first sentence and added another paragraph. (But I don’t have time to do this entry justice right now).

    Regarding the funny links: This is a remnant from the early dates of the nnLab. I don’t think there are many of these left.

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)