Talk:Dual graph/GA1

GA Review[edit]

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Reviewer: 99of9 (talk · contribs) 04:48, 6 October 2016 (UTC)[reply]

I'm up for reviewing this article. Glad to see the nomination @David Eppstein:. Bear with me, I'm a bit new at this! --99of9 (talk) 04:48, 6 October 2016 (UTC)[reply]

Rate	Attribute	Review Comment
1. Well-written:
	1a. the prose is clear, concise, and understandable to an appropriately broad audience; spelling and grammar are correct.	Spelling and grammar are fine. It's clear and concise enough, and there are wikilinks to required concepts.
	1b. it complies with the Manual of Style guidelines for lead sections, layout, words to watch, fiction, and list incorporation.
2. Verifiable with no original research:
	2a. it contains a list of all references (sources of information), presented in accordance with the layout style guideline.
	2b. reliable sources are cited inline. All content that could reasonably be challenged, except for plot summaries and that which summarizes cited content elsewhere in the article, must be cited no later than the end of the paragraph (or line if the content is not in prose).
	2c. it contains no original research.	One reference is authored by the primary Wikipedia author (also nominator). I have checked this reference in detail, and confirm that it was published in conference proceedings, has been broadly cited, and is relevant and balanced in this article. This does not constitute bias or original research according to our policies.
	2d. it contains no copyright violations or plagiarism.	I've done some spot tests. Hard to say definitively, but I think plagiarism is unlikely here.
3. Broad in its coverage:
	3a. it addresses the main aspects of the topic.	Perhaps a little history of when the concept of duals was first developed? Maybe some words on the wider applications/uses of this concept? Done
	3b. it stays focused on the topic without going into unnecessary detail (see summary style).	It would be tough and somewhat heavy on detail for the general reader, but is roughly appropriate for the more mathematically inclined audience who would come to this page.
	4. Neutral: it represents viewpoints fairly and without editorial bias, giving due weight to each.	One reference is authored by the primary Wikipedia author (also nominator). I have checked this reference in detail, and confirm that it was published in conference proceedings, has been broadly cited, and is relevant and balanced in this article. This does not constitute bias or original research according to our policies.
	5. Stable: it does not change significantly from day to day because of an ongoing edit war or content dispute.
6. Illustrated, if possible, by media such as images, video, or audio:
	6a. media are tagged with their copyright statuses, and valid non-free use rationales are provided for non-free content.	The image commons:File:Intercpunetring.png could do with a description template and ensuring that the "author" is linked properly to the (now-renamed) uploader. Done The image File:Noniso dual graphs.svg does not properly attribute the creator User:Drini of the PNG it was derived from File:Nonisomorphicdualgraps.png. Done The email associated with the image File:K6-Petersen duality.svg should be forwarded to the commons:Commons:OTRS system to ensure it is in the system. Done
	6b. media are relevant to the topic, and have suitable captions.
	7. Overall assessment.	Good job. Congrats.

Re the images: I moved the text on Intercpunetring.png into an Information template and fixed the link to the user, added text attributing the other image (although my own belief is that the graphs themselves are non-copyrightable, so an image that completely redraws them with a different layout as this one does has no actual copyright dependence on its predecessor), and forwarded the emails to OTRS. I assume it may take a little while for OTRS to read them and update the image data accordingly. —David Eppstein (talk) 00:09, 7 October 2016 (UTC)[reply]

Update: The OTRS information is now linked. —David Eppstein (talk) 01:00, 11 October 2016 (UTC)[reply]

Other comments[edit]

Lead[edit]

"(if G is connected)" deserves a wikilink or explanation of what you mean by connected. --99of9 (talk) 04:53, 6 October 2016 (UTC)[reply]

Related to this, I can't tell how to make a dual when dangling bond's are involved (see pic)...
What is the dual to this? The 4-6 edge does not "separate two faces from one another", so therefore does not get an edge in the dual? In which case how do you get node 6 of G back from H? Or should the dual have a loop from the outside "face" to itself?

It still has two faces on each side of it, they're just the same face as each other, so the dual vertex corresponding to that face has a self-loop. I've updated the article in an attempt to clarify this, as well as to link connected graph as suggested. —David Eppstein (talk) 05:14, 6 October 2016 (UTC)[reply]

Done lovely --99of9 (talk) 05:37, 6 October 2016 (UTC)[reply]

Dual polyhedra[edit]

In this section it would help to assert that all convex polyhedra (3d) can be represented as a plane graph, to connect with the definition used of a dual graph. I was led astray here because the link to convex polyhedron is redirected to convex polytope, which includes higher dimensions. Since I knew that a 4d hypercube graph wasn't a planar graph, it seemed to contradict the idea that you could necessarily find a dual. --99of9 (talk) 05:54, 6 October 2016 (UTC)[reply]
- Rewrote this section to give more of an introduction to polyhedral graphs, especially given your question in the next section of the review on self-dual graphs. —David Eppstein (talk) 00:16, 7 October 2016 (UTC)[reply]

Self duality[edit]

"there also exist self-dual graphs that are not polyhedral, such as the one shown". The one shown seems to be two tetrahedra connected by sharing a vertex in common. Is that still a polyhedron, albeit not convex? --99of9 (talk) 06:39, 6 October 2016 (UTC)[reply]
- No. "Polyhedral graph" is a technical term referring only to convex polyhedra. A polyhedral graph must be 3-connected (deleting up to two vertices keeps it connected) while in this case deleting the one shared vertex disconnects it. —David Eppstein (talk) 00:11, 7 October 2016 (UTC)[reply]

Simple vs multi[edit]

"cutset" is used before it is defined and wikilinked. --99of9 (talk) 12:23, 6 October 2016 (UTC)[reply]
- Glossed and linked at the first use. —David Eppstein (talk) 00:21, 7 October 2016 (UTC)[reply]

Uniqueness[edit]

"Whitney" is used before he is defined and wikilinked. --99of9 (talk) 12:41, 6 October 2016 (UTC)[reply]
"if it is a subdivision" ... please explain subdivision. --99of9 (talk) 12:44, 6 October 2016 (UTC)[reply]
- Linked Hassler Whitney and glossed and linked subdivision. —David Eppstein (talk) 00:24, 7 October 2016 (UTC)[reply]

Cuts and cutsets[edit]

What is a "*simple* cycle"? --99of9 (talk) 05:44, 7 October 2016 (UTC)[reply]
- I rewrote much of this section to clarify some of its terms, including this one. —David Eppstein (talk) 00:34, 8 October 2016 (UTC)[reply]

Suggested 3a expansions[edit]

I added a history section. Applications will require a bit more thought and research. Presumably it should at least include the duality of series-parallel circuits in CMOS design but there should be others. —David Eppstein (talk) 06:44, 24 October 2016 (UTC)[reply]