Five of the Thirteen Archimedean Solids Have Multiple English Names

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Four Archimedean Solids with Multiple English Names

I call the polyhedron above the rhombcuboctahedron. Other names for it are the rhombicuboctahedron (note the “i”), the small rhombcuboctahedron, and the small rhombicuboctahedron. Sometimes, the word “small,” when it appears, is put in parentheses. Of these multiple names, all of which I have seen in print, the second one given above is the most common, but I prefer to leave the “i” out, simply to make the word look and sound less like “rhombicosidodecahedron,” one of the polyhedra coming later in this post.

Trunc Cubocta

My preferred name for this polyhedron is the great rhombcuboctahedron, and it is also called the great rhombicuboctahedron. The only difference there is the “i,” and my reasoning for preferring the first name is the same as with its “little brother,” above. However, as with the first polyhedron in this post, the “i”-included version is more common than the name I prefer.

Unfortunately, this second polyhedron has another name, one I intensely dislike, but probably the most popular one of all — the truncated cuboctahedron. Johannes Kepler came up with this name, centuries ago, but there’s a big problem with it: if you truncate a cuboctahedron, you don’t get square faces where the truncated parts are removed. Instead, you get rectangles, and then have to deform the result to turn the rectangles into squares. Other names for this same polyhedron include the rhombitruncated cuboctahedron (given it by Magnus Wenninger) and the omnitruncated cube or cantitruncated cube (both of these names originated with Norman Johnson). My source for the named originators of these names is the Wikipedia article for this polyhedron, and, of course, the sources cited there.

Rhombicosidodeca

This third polyhedron (which, incidentally, is the one of the thirteen Archimedean solids I find most attractive) is most commonly called the rhombicosidodecahedron. To my knowledge, no one intentionally leaves out the “i” after “rhomb-” in this name, and, for once, the most popular name is also the one I prefer. However, it also has a “big brother,” just like the polyhedron at the top of this post. For that reason, this polyhedron is sometimes called the small rhombicosidodecahedron, or even the (small) rhombicosidodecahedron, parentheses included.

Trunc Icosidodeca

I call this polyhedron the great rhombicosidodecahedron, and many others do as well — that is its second-most-popular name, and identifies it as the “big brother” of the third polyhedron shown in this post. Less frequently, you will find it referred to as the rhombitruncated icosidodecahedron (coined by Wenninger) or the omnitruncated dodecahedron or icosahedron (names given it by Johnson). Again, Wikipedia, and the sources cited there, are my sources for these attributions.

While I don’t use Wenninger’s nor Johnson’s names for this polyhedron, their terms for it don’t bother me, either, for they represent attempts to reduce confusion, rather than increase it. As with the second polyhedron shown above, this confusion started with Kepler, who, in his finite wisdom, called this polyhedron the truncated icosidodecahedron — a name which has “stuck” through the centuries, and is still its most popular name. However, it’s a bad name, unlike the others given it by Wenninger and Johnson. Here’s why: if you truncate an icosidodecahedron (just as with the truncation of a cuboctahedron, described in the commentary about the second polyhedron pictured above), you don’t get the square faces you see here. Instead, the squares come out of the truncation as rectangles, and then edge lengths must be adjusted in order to make all the faces regular, once more. I see that as cheating, and that’s why I wish the name “truncated icosidodecahedron,” along with “truncated cuboctahedron” for the great rhombcuboctahedron, would simply go away.

Here’s the last of the Archimedean solids with more than one English name:

Trunc Cube

Most who recognize this shape, including myself, call it the truncated cube. A few people, though, are extreme purists when it comes to Greek-derived words — worse than me, and I take that pretty far sometimes — and they won’t even call an ordinary (Platonic) cube a cube, preferring “hexahedron,” instead. These same people, predictably, call this Archimedean solid the truncated hexahedron. They are, technically, correct, I must admit. However, with the cube being, easily, the polyhedron most familiar to the general public, almost none of whom know, let alone use, the word “hexahedron,” this alternate term for the truncated cube will, I am certain, never gain much popularity.

It is unfortunate that five of the thirteen Archimedean solids have multiple names, for learning to spell and pronounce just one name for each of them would be task enough. Unlike in the field of chemistry, however, geometricians have no equivalent to the IUPAC (International Union of Pure and Applied Chemists), the folks who, among other things, select official, permanent names and symbols for newly-synthesized elements. For this reason, the multiple-name problem for certain polyhedra isn’t going away, any time soon.

(Image credit:  a program called Stella 4d, available at www.software3d.com/Stella.php, was used to create all of the pictures in this post.)

Why Is Arkansas Political Geography Such a Mess?

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Why Is Arkansan Political Geography Such a Mess?

Technically, we live within the city limits of North Little Rock, but we’re surrounded by Maumelle, and also live in the Pulaski County Special School District, not the North Little Rock School District. Telling people we live in NLR causes confusion, so we say “Maumelle” instead, but mail won’t reach us unless it includes “North Little Rock” in the address. What’s more, that’s all in one county, Pulaski, near the center of the state.

The weirdness doesn’t stop there. Nearby is a city named Conway. I went to college there. It isn’t located in Conway County, though; that’s further West.

Head Southwest on I-30 from Little Rock, and you’ll soon encounter Benton (not in Benton County, although at least Bentonville is), and then get a chance to take an exit to go visit Hot Springs — but you won’t find it in Hot Spring County. Van Buren is right next to Oklahoma, and a long drive from Van Buren County. Is the City of Jacksonville to be found in Jackson County? Of course not — not in this state. Boonville, similarly, is not located in Boone County.

We have a Mississippi County here, and it borders two other states. We also have a long border with the state of Mississippi. However, Mississippi County, Arkansas isn’t one of several counties which do border the State of Mississippi. Instead, it borders Tennessee and Missouri.

Even things which seem intuitively obvious about my state’s political geography end up being wrong. Ask someone familiar with a U.S. map which state(s) you can find South of Arkansas, and they’ll almost certainly answer with Louisiana, perhaps including Texas, as well. However, the states of Oklahoma, Missouri, Tennessee, and Mississippi also include land that is South of carefully-chosen points in Arkansas. Here’s visual proof, which you can enlarge with a click:

arinus

Yes, all six states which border Arkansas are technically South of us, in a sense.

Perhaps the strangest thing about Arkansan political geography is that the town of Lonoke is actually in Lonoke County. It’s even their county seat. What are they trying to do there, confuse people?

Some Polygons with Irritating Names

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Some Polygons with Irritating Names

These polygons are known to virtually all speakers of English as the triangle and the quadrilateral, but that doesn’t mean I have to like that fact, and, the truth is, I don’t. Why? There are a couple of reasons, all involving lack of consistency with the established names of other polygons.

Consider the names of the next few polygons, as the number of sides increases: the pentagon, hexagon, heptagon, and octagon. The “-gon” suffix refers to the corners, or angles, of these figures, and is derived from Greek, The end of the word “triangle” also refers to the same thing — but not in Greek. For the sake of consistency, triangles should, instead, be called “trigons.”

In the case of the quadrilateral, the problem is twofold. The suffix “-lateral” refers to sides, not angles. For the sake of consistency, “-gon” should be used instead. The prefix “quadri-” does mean four, of course, but is derived from Latin, not Greek. We use the Greek prefix “tetra-” to refer to four when naming polyhedra (“tetrahedron”), so why not use it for polygons with four sides, also? The best name available for four-sided polygons requires a change in both the prefix and suffix of the word, resulting in the name “tetragon” for the figure on the right.

When I listed the names of higher polygons above, I deliberately stopped with the octagon. Here’s the next polygon, with nine sides and angles:

polygons

I’m guilty of inconsistency with the name of nine-sided polygons, myself. All over this blog, you can find references to “nonagons,” and the prefix “nona-” is derived from Latin. Those who already know better have, for years, been calling nine-sided polygons “enneagons,” using the Greek prefix for nine, rather than the Latin prefix, for reasons of consistency. I’m not going to go to the trouble to go back and edit every previous post on this blog to change “nonagon” to “enneagon,” at least right now, but, in future posts, I will join those who use “enneagon.”

Here’s one more, with eleven sides:

polygons

I don’t remember ever blogging about polygons with eleven sides, but I have told geometry students, in the past, that they are called “undecagons.” I won’t make that mistake again, for the derivation of that word, as is the case with “nonagon,” uses both Latin and Greek. A better name for the same figure, already in use, is “hendecagon,” and I’m joining the ranks of those who use that term, derived purely from Greek, effective immediately.

With “hendecagon” and “enneagon,” I don’t think use of these better names will cause confusion, given that they are already used with considerable frequency. Unfortunately, that’s not the case with the little-used, relatively-unknown words “trigon” and “tetragon,” so I’ll still be using those more-familiar names I don’t like, just to avoid being asked “What’s a trigon?” or “What’s a tetragon?” repeatedly, for three- and four-sided polygons. Sometimes, I must concede, it is necessary to choose the lesser of two irritations. With “triangle” and “quadrilateral,” this is one of those times.

Which State Is South of Arkansas?

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Which State Is South of Arkansas?

This really happened, in a geography class I took, long ago, in an Arkansas elementary school.

Teacher: “Which state is south of Arkansas?”

Me: “There are six: Oklahoma, Missouri, Tennessee, Mississippi, Louisiana, and Texas.”

Teacher: “No, Robert, that’s wrong.”

Me: “No, YOU’RE wrong. I’m right, and I’ll prove it.” I then got up, walked to the large classroom map of Arkansas, and ran my finger downwards on the map, six times, along the arrows you see above, while shouting, “South! South! South! South! South! South!” It’s true: from some point in Arkansas, you can travel, due South, into some part of any of the six adjacent states.

The teacher called my mother. Her response? “What’s the problem? He was RIGHT, wasn’t he?”