Wikipedia:Reference desk/Archives/Mathematics/2007 November 23

Mathematics desk
< November 22 << Oct | November | Dec >> November 24 >
Welcome to the Wikipedia Mathematics Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.


November 23 edit

Vertex degree: terminology for d(v) = n-1? edit

Does anybody know of some term used for a vertex connected to all other vertex, i.e. a vertex with degree n-1? None is listed under Degree (graph theory)#Special cases of degree value.

I was thinking of calling such a vertex "promiscuous", but since I'm not a native English speaker, I wonder if this would be prohibitively silly?

TIA, Phaunt (talk) 10:40, 23 November 2007 (UTC)[reply]

I think your suggestion would be properly "Prominent"... I would call it "Omni-Connected" but I don't know of any actually term being given besides "n-1". A math-wiki (talk) 12:34, 23 November 2007 (UTC)[reply]

Co-isolated was the just thing that came to my mind. I think I've been spending too much time on category theory. Algebraist 13:00, 23 November 2007 (UTC)[reply]
Thank you for your suggestions so far.
Thinking further, hub vertex and star vertex came to mind. The first is the name some authors give to the centre of a wheel graph; the second connotes the star graph (what? a red link? see here), though from a google scholar search, the second term seems to have been used in a different sense already. Searching a thesaurus for antonyms of 'isolated' (from the suggestion of 'co-isolated'), I came up with "sociable", but this may be just as silly as "promiscuous". (It invokes an idea of the vertices in my graphs having a social life which I may not be comfortable with....) Phaunt (talk) 13:58, 23 November 2007 (UTC)[reply]
"Graph center"; not quite, but close. —Preceding unsigned comment added by 84.187.113.101 (talk) 21:46, 23 November 2007 (UTC)[reply]
"Fully connected vertex" is a bit of a mouthful, but should hopefully express the issue without ambiguity. If you want a monosyllable, I kind of like "hub". Just remember to define it clearly. Not that there's IMHO anything wrong with "promiscuous", either — much sillier terms have been used by quite respectable mathematicians. —Ilmari Karonen (talk) 17:00, 24 November 2007 (UTC)[reply]
List of silly mathematical terms – No? How disappointing. —Tamfang (talk) 01:22, 30 December 2007 (UTC)[reply]