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1. • CommentRowNumber1.
   • CommentAuthorKeithEPeterson
   • CommentTimeDec 16th 2016
   • PermaLink
   Author: KeithEPeterson
   Format: MarkdownItexAdded the page [partition logic](https://ncatlab.org/nlab/show/partition+logic). Will breathe more life into it.

   Added the page partition logic. Will breathe more life into it.

2. • CommentRowNumber2.
   • CommentAuthorKeithEPeterson
   • CommentTimeDec 16th 2016
   • (edited Dec 16th 2016)
   • PermaLink
   Author: KeithEPeterson
   Format: MarkdownItexWhat would be the best way to say that partition logic is dual to subset logic in an nlab way? The paper I'm referencing: [The Logic of Partitions: Introduction to the Dual of the Logic of Subsets](https://arxiv.org/pdf/0902.1950v2.pdf).

   What would be the best way to say that partition logic is dual to subset logic in an nlab way?

   The paper I’m referencing: The Logic of Partitions: Introduction to the Dual of the Logic of Subsets.

3. • CommentRowNumber3.
   • CommentAuthorRodMcGuire
   • CommentTimeDec 17th 2016
   • PermaLink
   Author: RodMcGuire
   Format: MarkdownItexI came across that paper before and got the impression that the author was a dilettante and/or crackpot. In category theory the [[quotient object]] lattice of a set is dual to its [[subobject]] lattice in the sense that the first uses surjections while the second uses injections. In briefly relooking at that paper I see that he argues why his partition lattice has to be opposite (upside down) to the natural quotient object lattice without seeming to be aware of quotient objects lattices. I guess he may have started off a ways back looking at a partition lattice in his favorite orientation and has since tried to graft on category theoretical notions. About the only one [who cites that paper](https://scholar.google.com/scholar?oe=utf-8&um=1&ie=UTF-8&lr&cites=13661312157712347432) is the author himself, and he does so a lot. I'd be happy if you could show he was really saying something worthwhile reading. For what it is worth he has a more recent 2014 paper [An introduction to partition logic](https://philpapers.org/archive/ellait-6.pdf) which seems to be pretty much the same as the 2011 paper.

   I came across that paper before and got the impression that the author was a dilettante and/or crackpot.

   In category theory the quotient object lattice of a set is dual to its subobject lattice in the sense that the first uses surjections while the second uses injections.

   In briefly relooking at that paper I see that he argues why his partition lattice has to be opposite (upside down) to the natural quotient object lattice without seeming to be aware of quotient objects lattices. I guess he may have started off a ways back looking at a partition lattice in his favorite orientation and has since tried to graft on category theoretical notions.

   About the only one who cites that paper is the author himself, and he does so a lot.

   I’d be happy if you could show he was really saying something worthwhile reading. For what it is worth he has a more recent 2014 paper An introduction to partition logic which seems to be pretty much the same as the 2011 paper.

4. • CommentRowNumber4.
   • CommentAuthorKeithEPeterson
   • CommentTimeDec 17th 2016
   • PermaLink
   Author: KeithEPeterson
   Format: MarkdownItexVery well. Is there a way to remove pages?

   Very well.

   Is there a way to remove pages?

5. • CommentRowNumber5.
   • CommentAuthorTodd_Trimble
   • CommentTimeDec 17th 2016
   • PermaLink
   Author: Todd_Trimble
   Format: MarkdownItex"Crackpot" would, I think, be way too harsh. "Dilettante": well, I can think of well-regarded mathematicians who strike me as dilettantish in some respects. David Ellerman is a philosopher at UC Riverside, where John Baez is tenured. He has also written on heteromorphisms. It happens that I am in correspondence with a young man about his papers cited at [[heteromorphism]], which personally I do not find compelling but which others besides him seem to cite here and there. Having said all that, I agree with Rod that I'm not sure the partition logic paper is noteworthy enough to devote a big nLab article to. But let me add that lattices of partitions are intensively studied in lattice theory, being a fundamental example of a [geometric lattice](https://en.wikipedia.org/wiki/Geometric_lattice) (related to [[matroid]]) and have interesting applications in combinatorics. For example, Joyal related their homology to the Lie operad in SLNM 1234. So what I might propose is that someone start an article [[partition lattice]] which mentions some of these things, including the Ellerman paper if that seems warranted. I could maybe start that in a few days or over Christmas break if no one else does. Rod of course is also correct that in an exact category, $Quot(X)$ is dual to $Equiv(X \times X)$ which sits inside $Sub(X \times X)$ as a meet semi-lattice.

   “Crackpot” would, I think, be way too harsh. “Dilettante”: well, I can think of well-regarded mathematicians who strike me as dilettantish in some respects.

   David Ellerman is a philosopher at UC Riverside, where John Baez is tenured. He has also written on heteromorphisms. It happens that I am in correspondence with a young man about his papers cited at heteromorphism, which personally I do not find compelling but which others besides him seem to cite here and there.

   Having said all that, I agree with Rod that I’m not sure the partition logic paper is noteworthy enough to devote a big nLab article to. But let me add that lattices of partitions are intensively studied in lattice theory, being a fundamental example of a geometric lattice (related to matroid) and have interesting applications in combinatorics. For example, Joyal related their homology to the Lie operad in SLNM 1234. So what I might propose is that someone start an article partition lattice which mentions some of these things, including the Ellerman paper if that seems warranted. I could maybe start that in a few days or over Christmas break if no one else does.

   Rod of course is also correct that in an exact category, $Quot(X)$ is dual to $Equiv(X \times X)$ which sits inside $Sub(X \times X)$ as a meet semi-lattice.

6. • CommentRowNumber6.
   • CommentAuthorTobyBartels
   • CommentTimeDec 18th 2016
   • PermaLink
   Author: TobyBartels
   Format: MarkdownItexTo remove a page, look at [category: empty](https://ncatlab.org/nlab/list/empty) and see which number should be used next, then rename the page to `empty ###` using that number. Replace the content (including the automatically added redirect with `category: empty`. (To remove the backlog of empty pages, one should also create pages by reversing this process, although it\'s easy to forget to do that.)

   To remove a page, look at category: empty and see which number should be used next, then rename the page to empty ### using that number. Replace the content (including the automatically added redirect with category: empty.

   (To remove the backlog of empty pages, one should also create pages by reversing this process, although it's easy to forget to do that.)

7. • CommentRowNumber7.
   • CommentAuthorKeithEPeterson
   • CommentTimeDec 18th 2016
   • PermaLink
   Author: KeithEPeterson
   Format: MarkdownItexI take it that's buried somewhere in the howto...

   I take it that’s buried somewhere in the howto…

8. • CommentRowNumber8.
   • CommentAuthorTobyBartels
   • CommentTimeDec 19th 2016
   • PermaLink
   Author: TobyBartels
   Format: MarkdownItexI don\'t think that it is, actually!

   I don't think that it is, actually!

9. • CommentRowNumber9.
   • CommentAuthorMike Shulman
   • CommentTimeDec 19th 2016
   • PermaLink
   Author: Mike Shulman
   Format: MarkdownItexIt should be.

   It should be.

10. • CommentRowNumber10.
    • CommentAuthorTodd_Trimble
    • CommentTimeDec 19th 2016
    • PermaLink
    Author: Todd_Trimble
    Format: MarkdownItexI just added a subsection to [[HowTo]], How to remove a page, pasting in Toby's #6.

    I just added a subsection to HowTo, How to remove a page, pasting in Toby’s #6.

11. • CommentRowNumber11.
    • CommentAuthorRodMcGuire
    • CommentTimeDec 19th 2016
    • (edited Dec 19th 2016)
    • PermaLink
    Author: RodMcGuire
    Format: MarkdownItex> So what I might propose is that someone start an article [[partition lattice]] which mentions some of these things, including the Ellerman paper if that seems warranted. I could maybe start that in a few days or over Christmas break if no one else does. I may be able to provide some nice SVG images for that. See: [Sandbox#838](https://ncatlab.org/nlab/revision/Sandbox/838). However when I tried to use SVG `<use ...>` it turned up some Instiki bugs that Jacques Distler has since fixed but the fix hasn't yet been propagated into the nLab. (Using `use` makes including SVG pictures in math equations a good bit less painful). I'm currently slowly working on a new version of the software to generate the SVG which I don't know when will be functioning, If pictures are really needed I might be able to make the old version produce them.

    So what I might propose is that someone start an article partition lattice which mentions some of these things, including the Ellerman paper if that seems warranted. I could maybe start that in a few days or over Christmas break if no one else does.

    I may be able to provide some nice SVG images for that. See: Sandbox#838.

    However when I tried to use SVG <use ...> it turned up some Instiki bugs that Jacques Distler has since fixed but the fix hasn’t yet been propagated into the nLab. (Using use makes including SVG pictures in math equations a good bit less painful). I’m currently slowly working on a new version of the software to generate the SVG which I don’t know when will be functioning, If pictures are really needed I might be able to make the old version produce them.