Jump to content

User talk:Dysprosia/Archive (11)

Page contents not supported in other languages.
From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Dysprosia (talk | contribs) at 01:57, 16 June 2004 (copy here). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Old talk in archive: User talk:Dysprosia/Archive -- User talk:Dysprosia/Archive (2) -- User talk:Dysprosia/Archive (3) -- User talk:Dysprosia/Archive (4) -- User talk:Dysprosia/Archive (5) -- User talk:Dysprosia/Archive (6) -- User talk:Dysprosia/Archive (7) -- User talk:Dysprosia/Archive (8) -- User talk:Dysprosia/Archive (9) -- User talk:Dysprosia/Archive (10) (most recent)



Licence

Please add the licence information by the picture Image:Water molecule dimensions.png becuase i want to use it in the german wikipedia.Thanks for your help!--80.171.23.185 16:58, 15 Jun 2004 (UTC)

Done. Dysprosia 01:49, 16 Jun 2004 (UTC)

Hasse diagram

I think you miss the subtlety of the point I added at Hasse diagram. The fact is that one need not define the structure of the diagram in terms of a cover relation, but can bypass this and just do so in terms of the relation itself and omit self-loops.

I think you're the one who's missing something, and it's not very subtle. If one did what you propose, then the Hasse diagram for the partition lattice would look like this:

File:Partition2.jpg

(and that's just the strict inequality, without the "loops")

... rather than like this:

File:PartitionLattice.jpg

That is why the cover relation is used.

Perhaps it is more common to define the structure in terms of a cover relation, and perhaps it is "better" in some way to do this, but do you think it is best to leave the point out about bypassing the cover relation entirely - as it is possible to do so, is it not? Dysprosia 13:59, 15 Jun 2004 (UTC)

No, it is not, unless you want the diagram to become much too crowded, needlessly, as above. Michael Hardy 20:15, 15 Jun 2004 (UTC)

Ok, I think I've found the problem. Presumably in your "over-crowded" diagram you ignore the requirement of only representing an edge between a vertex and its immediate predecessor, this, of course, is necessary also.

That's what the cover relation is!!

I still think that having to write it in terms of introducing another relation is a little cumbersome.

You mean calling it by a different name, the "cover relation", rather than saying "only representing an edge between a vertex and its immediate predecessor", is what makes it too cumbersome for you?

I have something in mind for the page - it would be nice to be as explicit as possible and perhaps introduce why we use a cover relation because of this, but I'd be interested to know what you think. Dysprosia 22:18, 15 Jun 2004 (UTC)

Of course it is!!!! (Come, come, Michael, you need not use gratuitous exclamation with me.) Have you not realised that maybe I want to add to the article why we use it, instead of jumping in and introducing another bit of terminology to sweep some of the dirty details under the carpet? Doing that makes the text less expressive, in my mind. Dysprosia 22:29, 15 Jun 2004 (UTC)

OK, I've edited the article so that it first says what the thing looks like as a drawing on a page, and then defines the cover relation as a translation of that idea into more abstract language. Michael Hardy 22:31, 15 Jun 2004 (UTC)
That's not what I have in mind or am intending. I have to leave right now, but I'll try something a bit more explicit in the article on my return. Dysprosia 22:35, 15 Jun 2004 (UTC)
Done. I hope you don't find too much at fault with what I've done. Dysprosia 01:49, 16 Jun 2004 (UTC)
I've just rearranged it a bit, putting the long discussion after the easy part. Michael Hardy 01:54, 16 Jun 2004 (UTC)


That seems to me to be a little odd - should we not motivate (and also mention) the ideas and concepts before we use them? Dysprosia 01:57, 16 Jun 2004 (UTC)