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The amssymb package has a binary relation symbol named \between, which I have never come across.

What is it used for?
I found out from a compiler error when I tried to define a symbol named that way myself, and I am now wondering whether it is a symbol I could use for my purpose.

\between

Qrrbrbirlbel
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    I wonder if there is any efficient way to find all ArXiv papers that contain \between in their Latex source code? – Jukka Suomela Nov 01 '10 at 09:23
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    This is an interesting question, and I'm curious to find the answer, but I can't help it would be better placed at the mathematics stackexchange: It's not really a question about LaTeX... http://math.stackexchange.com/ – Seamus Nov 01 '10 at 11:39
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    Never seen it before. It's in unicode, though: http://www.fileformat.info/info/unicode/char/226c/index.htm – Matthew Leingang Nov 01 '10 at 14:15
  • @Caramdir: Thanks for the edit! (new at this..) –  Nov 01 '10 at 16:48
  • That's a closing parenthesis telling the open parenthesis "If I'd be any closer to you I'd be behind you" :-) – Victor Eijkhout May 22 '22 at 01:34

5 Answers5

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I found it in the Journal of Combinatorial Optimization (2007) 13:217-221, February 14, 2007: A 2-approximation for the preceding-and-crossing structured 2-interval pattern problem. There the expression \{<,\between\} has been used, as can be seen in the abstract.

Regarding intervals, \between \between may stand for a crossing/overlapping relation like < for a precedence order and kind of a subset symbol for inclusion/nesting. See also Extracting constrained 2-interval subsets in 2-interval sets.

In such difficult cases, the LaTeX search engine of Springer is a useful tool (now discontinued).

Glorfindel
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Stefan Kottwitz
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  • That's quite a lot of definitions given in a short 5 page paper. @Stefan: how did you actually perform this feat of finding where a symbol is used? – Willie Wong Nov 01 '10 at 15:35
  • @Willie: I used Google Code search. – We Are All Monica Nov 01 '10 at 15:57
  • That's just great, thanks! And I too would like to know how you found the symbol (which in your case is clearly not with Google Code Search). –  Nov 01 '10 at 16:47
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    @Alright @Willie: I used the Springer LaTeX search. I will add that to the answer. – Stefan Kottwitz Nov 01 '10 at 19:34
  • Great link. And the search for \between yields just this one result ... – Hendrik Vogt Nov 02 '10 at 09:03
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    Once found the relation to intervals, google image search (for interval subsets or 2-intervals) restricted to tiny images immediately gave the other result. Other ways to try in general might be google with options filetype:tex and perhaps additionally site:arxiv.org. – Stefan Kottwitz Nov 02 '10 at 12:11
  • I found a nice definition on the bottom of the second page of this author's preprint: https://people.mpi-inf.mpg.de/~hermelin/Journal%20Publications/2-interval.pdf – Toby Bartels Nov 30 '16 at 18:50
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    Briefly, given two intervals I = (a,b) and J = (c,d), there are (barring coincidences) 6 possible relative orders of a, b, c, and d, giving the 6 results I < J, J < I, I ⊏ J, J ⊏ I, I ≬ J, and J ≬ I, with the symbols to be read ‘precedes’, ‘is nested in’, and ‘crosses’ (not ‘is between’). – Toby Bartels Nov 30 '16 at 18:56
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It is not new. It appears on page 28 of "Kummer's quartic surface" by R W H T Hudson (Cambridge University Press 1905, republished 1990; WorldCat) without explanation, so was presumably well understood by Projective Geometrists then.

It was used by Hudson in "Kummer's Quartic Surface" to denote the inner product of two single-row matrices, for instance (a,b,c,d≬x,y,z,t) = ax+by+cz+dt. The advantage of the notation seems slight and may merely have saved space by not having to write the second matrix as a vertical column in the usual way.

Nick Matteo
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J F James
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    Further to my last note, it was used by Hudson in "Kummer's Quartic Surface" to denote the inner product of two single-row matrices, for instance (a,b,c,d≬x,y,z,t) = ax+by+cz+dt. The advantage of the notation seems slight and may merely have saved space by not having to write the second matrix as a vertical column in the usual way. – J F James Nov 24 '12 at 15:03
  • The notation goes back to Cayley, see https://tex.stackexchange.com/q/487643/4427 – egreg Dec 10 '20 at 09:24
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It's a mathematical symbol. I use ≬ in genealogy. Dates are often imprecise. The widow's husband dies in 1780 and she is listed as deceased in her son's marriage bond in 1799. So she died ≬1780-99.

David A Stumpf
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In constructive mathematics and pointfree topology, "A ≬ B" means that the sets A and B have an element in common. Constructively, this condition is stronger than merely stating that the intersection A ∩ B is not empty, and appears in many places. Hence it makes sense to have a special symbol for it.

I don't know who introduced this notation, might be Giovanni Sambin, but in any case Peter Schuster and Daniel Misselbeck-Wessel are often using the symbol in their papers. To cite just one example: Eliminating disjunction by disjunction elimination

Ingo Blechschmidt
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  • I might ask Peter: his office is two doors from mine. – egreg Feb 09 '23 at 22:26
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    Peter Schuster answered to my mail: he says to have taken the symbol from Sambin's papers (by the way, Sambin was one of my teachers during the PhD), but that he's pretty sure to have seen the symbol also in some short paper by Ore, maybe with the same meaning. – egreg Feb 10 '23 at 11:01
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I have never seen it before so I'm not sure where it comes up. That said, as long as you define your symbols, you can use them for whatever purpose you want. People might be confused if you redefine + as -, but I suspect that \between is sufficiently specialized that you can repurpose it as you wish.

TH.
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  • I know. But I usually try to come up with as little new notation as possible. And the name of the symbol is suggestive enough to make me wonder whether other people already have a notation (that symbol) for the same thing. –  Nov 01 '10 at 16:45