Talk:Dual graph/GA1

GA Review
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Reviewer: 99of9 (talk · contribs) 04:48, 6 October 2016 (UTC)

I'm up for reviewing this article. Glad to see the nomination. Bear with me, I'm a bit new at this! --99of9 (talk) 04:48, 6 October 2016 (UTC)
 * 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)
 * Update: The OTRS information is now linked. —David Eppstein (talk) 01:00, 11 October 2016 (UTC)

Lead

 * "(if G is connected)" deserves a wikilink or explanation of what you mean by connected. --99of9 (talk) 04:53, 6 October 2016 (UTC)
 * Related to this, I can't tell how to make a dual when dangling bond's are involved (see pic)... 6n-graf.svg
 * 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)
 * ✅ lovely --99of9 (talk) 05:37, 6 October 2016 (UTC)

Dual polyhedra

 * 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)
 * 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)

Self duality

 * "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)
 * 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)

Simple vs multi

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

Uniqueness

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

Cuts and cutsets

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

Suggested 3a expansions

 * 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)