# 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

## Site Tag Cloud

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

• CommentRowNumber1.
• CommentAuthorDavidRoberts
• CommentTimeApr 28th 2010

The pages generalized continuity and partially ordered dagger-category promote the article ’Funcoids and reloids’. I’m not an expert on filters and so forth (which are used a lot in the aforementioned article) so cannot judge the merits of the work, but it has been mentioned here before that the author asks on his webpage to be nominated for the Abel prize. Needless to say, I’m of the opinion that the work presented there is not on par with that of other Abel prize winners. I don’t mind having relevant and constructive material being extracted from said article, but I hesitate to have a stub here then a link to a long pdf article which is very much a working document. If there are working documents, they should be nlab pages. As nlab users we cannot edit this document, and this could start a slippery slope where anyone can put on a stub of their favourite (legitimate, but inconsequential) construction and then link to their own webpage or articles where any tack is taken. We’ve seen this before, and no one wants to repeat it.

That being said, if an interesting and useful generalisation of a proximity space can be winkled out, then I’m happy for the material to be included on the nlab. I may even be blowing the whole thing out of proportion, so I hesitate to edit ruthlessly where my initial urge told me to.

• CommentRowNumber2.
• CommentAuthorHarry Gindi
• CommentTimeApr 28th 2010
• (edited Apr 28th 2010)

Porton doesn't know what he's talking about. I know him from IRC. He's a complete and total moron as well as a crank. Even leaving that article up will damage the nLab's credibility.

Filters are easy to understand. They're upper sets of a poset such that all cospans are squarable.

• CommentRowNumber3.
• CommentAuthorDavidRoberts
• CommentTimeApr 28th 2010

all cospans are squarable.

by which I think you mean every diagram of shape $a \leftarrow b \rightarrow c$ has a cocone?

• CommentRowNumber4.
• CommentAuthorMike Shulman
• CommentTimeApr 28th 2010

Of course, David only said he wasn’t an expert on filters, not that he didn’t know the definition – which anyway can be found at filter. (-:

I think taking down stubs that are only links of that sort is perfectly reasonable. Regardless of the merit of the work in question, the nlab is not a dumping ground for links to personal work.

• CommentRowNumber5.
• CommentAuthorDavidRoberts
• CommentTimeApr 28th 2010

I made some edits at partially ordered dagger-category, by the way, and removed the link there to Funcoids and reloids.

• CommentRowNumber6.
• CommentAuthorDavidRoberts
• CommentTimeApr 28th 2010
• (edited Apr 28th 2010)

And replaced the contents of generalized continuity with ’blanked’. I don’t know if there is a decent sort of protocol about this, but this doesn’t count as spam. I’ll check some old JA pages to see what Toby did. Edit: Hmm, he didn’t kill it completely, but left a link to JA’s wiki page elsewhere. Anyway, this is just a flag to let people know what I’ve done. It can of course be rolled back if it is deemed inappropriately strong.

Actually I think I’ll roll it back myself, and let wiser heads deal with it.

• CommentRowNumber7.
• CommentAuthorHarry Gindi
• CommentTimeApr 28th 2010
• (edited Apr 28th 2010)

Actually I think I'll roll it back myself, and let wiser heads deal with it.

Because you didn't do it, you forced my hand. I wouldn't say that I'm a "wiser head", but I know this moron from IRC for around a year.

I blanked both partially ordered dagger-category and generalized continuity because they were made up by Victor Porton, who just a few days ago I noted as being a complete idiot and crackpot. Note that Porton often comes on IRC to ask completely idiotic and basic questions about filters and asks people to collaborate with him on his many "projects".

Having those pages on the nLab can do nothing more than damage the Lab's credibility.

1. I’ve edited both pages in a more diplomatic style.

• CommentRowNumber9.
• CommentAuthorUrs
• CommentTimeApr 28th 2010
• (edited Apr 28th 2010)

Wait. The author may be going off a tangent and it is good to not have him abuse the nLab for promoting dubious material, but at least around revision 13 of the entry, when I looked at it, it seemed to be about a concept that in principle is reasonable. In fact Tim Porter back then added the entry on the special case of partially ordered groupoids, which makes the impression of being a quite respectable topic, going back to Ehresmann.

Maybe we could distinguish better between acceptable basic material and odd material being built on it. Would harm be done if we simply reverted back to around revision number 13, but removing the link to the funky “Funcoids” ?

2. that’s perfectly fine for me, I think that even an idea with dobious origins can be well developed in something interesting. that’s why I wrote “temporarly blanked”. let us discuss and see what to do. my vote: I perfectly agree with Urs staring back from revision 13 there, removing the link to funcoids.

• CommentRowNumber11.
• CommentAuthorUrs
• CommentTimeApr 28th 2010

In any case, it hurts me to see material added by Tim Porter be blanked. We should at the very least retain the references he gave in an entry on partially ordered groupoids.

• CommentRowNumber12.
• CommentAuthorDavidRoberts
• CommentTimeApr 28th 2010

Arrrgh! Network is really playing up, and I lost comments here and edits to partially ordered dagger-category, which I had rolled back and was putting into a more acceptable shape.

Now I’ve done it again, I hope it is more up to scratch.

• CommentRowNumber13.
• CommentAuthorDavidRoberts
• CommentTimeApr 28th 2010

Sorry for doing this unilaterally, but I’d already started fixing it when the page was ’blanked’ (removing link to Funcoids for a start). I really only wanted the page generalized continuity sorted, as it was clearly an unmotivated stub merely there to host the Funcoids link.

• CommentRowNumber14.
• CommentAuthorUrs
• CommentTimeApr 28th 2010

Thanks, David, for taking care of this. I am wondering if we should have a separate page on locally ordered groupoids?

• CommentRowNumber15.
• CommentAuthordomenico_fiorenza
• CommentTimeApr 28th 2010
• (edited Apr 28th 2010)

axioms for an ordered groupoid produce something totally weird for 1-object groupoids; I guess axiom “$x\leq y$ implies $x^{-1}\leq y^{-1}$” is a typo for “$x\leq y$ implies $y^{-1}\leq x^{-1}$, which is more natural with experience of usual orders on $(\mathbb{Z},+)$ od $(\mathbb{R}^*,\cdot)$, and is consistent with the axiom “$x\leq y$ and $u\leq v$ imply $x u\leq y v$”. namely, $x\leq y$ in a 1-object groupoid implies $x^{-1}x\leq x^{-1}y$ and so $y^{-1}\leq x^{-1}y y^{-1}$.

based on this I think the defining axiom (1) for partially ordered dagger categories should be reverted into $f\subseteq g \Leftrightarrow g^\dagger\subseteq f^\dagger$.

by the way, why are we using $\subseteq$ for $\leq$ in that entry?

• CommentRowNumber16.
• CommentAuthorTim_Porter
• CommentTimeApr 28th 2010

For the record: The main recent results on `ordered groupoid' relate to their link with inverse semigroups. see book by Mark Lawson. That is very pretty stuff. The ordered groupoids have a neat homotopy theory which Mark and I with a student of his, Joe Matthews, wrote up some years ago. It is fun stuff.

• CommentRowNumber17.
• CommentAuthorUrs
• CommentTimeApr 28th 2010

by the way, why are we using $\subseteq$ for $\leq$ in that entry?

I think that’s due to the outsider-contributor in question. You should change it.

3. You should change it.

yes, but what about the order reversing? I’ll wait for feedback on that before editing the entry.

• CommentRowNumber19.
• CommentAuthorHarry Gindi
• CommentTimeApr 28th 2010

@Tim: I didn't realize before blanking the page that you'd written part of it. Sorry about that!

• CommentRowNumber20.
• CommentAuthorTim_Porter
• CommentTimeApr 28th 2010

Don't worry.

• CommentRowNumber21.
• CommentAuthorSridharRamesh
• CommentTimeApr 28th 2010

There is, incidentally, already an article on locally partially ordered categories, to which I’ve added a link from the partially ordered dagger-category article, though perhaps, since the latter seems to simply redefine the former in its first a half, a greater degree of merging is called for.

• 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)