Bourbaki dangerous bend symbol: Difference between revisions
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{{Short description|Typological symbol representing difficulty}} |
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| ⚫ | The '''dangerous bend''' or '''caution''' symbol '''☡''' ({{unichar|2621|CAUTION SIGN}}) was created by the [[Nicolas Bourbaki]] group of mathematicians and appears in the margins of [[mathematics]] books written by the group. It resembles a [[Traffic sign|road sign]] that indicates a "dangerous bend" in the road ahead, and is used to mark passages tricky on a first reading or with an especially difficult argument.<ref>Steven G. Krantz (2011), ''[https://books.google.com/books?id=mMZBtxVZiQoC&pg=PA92 The Proof Is in the Pudding: The Changing Nature of Mathematical Proof]'', Springer, {{ISBN |0-387-48908-8}}, p. 92.</ref> |
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|quote={{lang|fr|Certains passages sont destinés à prémunir le lecteur contre des erreurs graves, où il risquerait de tomber; ces passages sont signalés en marge par le signe ☡ (« tournant dangereux »)}} |
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Some passages are designed to forewarn the reader against serious errors, where he risks falling; these passages are |
Some passages are designed to forewarn the reader against serious errors, where he risks falling; these passages are indicated in the margin with the sign ☡ ("dangerous bend") |
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</p> |
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|source= |
|source=Nicolas Bourbaki's description of the symbol in several textbooks<ref>See, for example, ''[https://books.google.com/books?id=VDGifaOQogcC&pg=SA1-PA5 Théorie des ensembles]'', p. I-8.</ref> |
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==Variations== |
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| ⚫ | The '''dangerous bend''' or '''caution''' symbol ☡ ( |
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| ⚫ | Others have used variations of the symbol in their books. The computer scientist [[Donald Knuth]] introduced an American-style road sign depiction in his [[Metafont]] and [[TeX]] systems, with a pair of adjacent signs indicating doubly dangerous passages.<ref>Donald Ervin Knuth (1986), ''[https://books.google.com/books?id=GghUAAAAMAAJ The METAFONTbook]'', Addison-Wesley, {{ISBN |0-201-13445-4}}.</ref><ref>Donald Ervin Knuth (1984), ''[https://books.google.com/books?id=hEYuAQAAIAAJ The TeXbook]'', Addison-Wesley, {{ISBN |0-201-13448-9}}.</ref><ref>George J. Tourlakis (2003), ''[https://books.google.com/books?id=nparMXao59QC&pg=PR14 Lectures in Logic and Set Theory, Volume 2: Set Theory]'', Cambridge University Press, {{ISBN |0-521-75374-0}}, p. xiv.</ref><ref>Gerard P. Michon (2012), ''[http://www.numericana.com/answer/symbol.htm#db Dangerous Bend Symbol, doubled and tripled]'', Numericana.</ref> |
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| ⚫ | Others have used variations of the symbol in their |
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==Typography== |
==Typography== |
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[[File: |
[[File:Knuth's dangerous bend symbol.svg|thumb|60px|right|Knuth's "Dangerous Bend" sign, with yellow color added.]] |
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In HTML the unicode dangerous bend symbol ☡ can be produced by: |
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:<tt>&#x2621;</tt> |
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In the [[LaTeX]] typesetting system, Knuth's dangerous bend symbol can be produced by |
In the [[LaTeX]] typesetting system, Knuth's dangerous bend symbol can be produced by |
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first loading the font manfnt (a font with extra symbols used in Knuth's TeX manual) with |
first loading the font manfnt (a font with extra symbols used in Knuth's TeX manual) with <code> |
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\usepackage{manfnt}</code> and then typing <code>\dbend</code> |
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and then typing |
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:<tt>\dbend</tt> |
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and <tt>\textreversedvideodbend</tt>. |
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==In popular culture== |
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The [[Twenty One Pilots]] song "[[Overcompensate (song)|Overcompensate]]", makes direct reference to the symbol. Since 2018, the Nicolas Bourbaki group has also been referenced in the conceptual narrative of the band.<ref name=Billboard>{{Cite magazine |last=Kaufman |first=Gil |date=February 29, 2024 |title=Twenty One Pilots Announce 'Clancy' Album, Drop Video For Booming 'Overcompensate' Single |url=https://www.billboard.com/music/rock/twenty-one-pilots-clancy-album-overcompensate-single-1235618630/ |access-date=March 1, 2024 |magazine=Billboard}}</ref><ref>{{Cite web|url=http://dmaorg.info/found/15398642_14/img/6629097cc6e3/_ti_su_p.png|title=Map of Dema|website=dmaorg.info|access-date=October 7, 2018}}</ref> |
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==See also== |
==See also== |
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*[[Halmos box]] |
*[[Halmos box]] |
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==External links== |
==External links== |
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[[Category:Mathematical symbols]] |
[[Category:Mathematical symbols]] |
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[[Category:Nicolas Bourbaki|*]] |
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{{Visual-symbol-stub}} |
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[[hu:Bourbaki veszélyes útkanyarulat]] |
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[[pl:Niebezpieczny zakręt]] |
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Latest revision as of 15:56, 1 May 2024
The dangerous bend or caution symbol ☡ (U+2621 ☡ CAUTION SIGN) was created by the Nicolas Bourbaki group of mathematicians and appears in the margins of mathematics books written by the group. It resembles a road sign that indicates a "dangerous bend" in the road ahead, and is used to mark passages tricky on a first reading or with an especially difficult argument.[1]
Certains passages sont destinés à prémunir le lecteur contre des erreurs graves, où il risquerait de tomber; ces passages sont signalés en marge par le signe ☡ (« tournant dangereux »)
Some passages are designed to forewarn the reader against serious errors, where he risks falling; these passages are indicated in the margin with the sign ☡ ("dangerous bend")
Nicolas Bourbaki's description of the symbol in several textbooks[2]
Variations[edit]
Others have used variations of the symbol in their books. The computer scientist Donald Knuth introduced an American-style road sign depiction in his Metafont and TeX systems, with a pair of adjacent signs indicating doubly dangerous passages.[3][4][5][6]
Typography[edit]
In the LaTeX typesetting system, Knuth's dangerous bend symbol can be produced by
first loading the font manfnt (a font with extra symbols used in Knuth's TeX manual) with
\usepackage{manfnt} and then typing \dbend
There are several variations given by \lhdbend, \reversedvideodbend, \textdbend, \textlhdbend, and \textreversedvideodbend.
In popular culture[edit]
The Twenty One Pilots song "Overcompensate", makes direct reference to the symbol. Since 2018, the Nicolas Bourbaki group has also been referenced in the conceptual narrative of the band.[7][8]
See also[edit]
References[edit]
- ^ Steven G. Krantz (2011), The Proof Is in the Pudding: The Changing Nature of Mathematical Proof, Springer, ISBN 0-387-48908-8, p. 92.
- ^ See, for example, Théorie des ensembles, p. I-8.
- ^ Donald Ervin Knuth (1986), The METAFONTbook, Addison-Wesley, ISBN 0-201-13445-4.
- ^ Donald Ervin Knuth (1984), The TeXbook, Addison-Wesley, ISBN 0-201-13448-9.
- ^ George J. Tourlakis (2003), Lectures in Logic and Set Theory, Volume 2: Set Theory, Cambridge University Press, ISBN 0-521-75374-0, p. xiv.
- ^ Gerard P. Michon (2012), Dangerous Bend Symbol, doubled and tripled, Numericana.
- ^ Kaufman, Gil (February 29, 2024). "Twenty One Pilots Announce 'Clancy' Album, Drop Video For Booming 'Overcompensate' Single". Billboard. Retrieved March 1, 2024.
- ^ "Map of Dema". dmaorg.info. Retrieved October 7, 2018.
External links[edit]
- Knuth's use of the dangerous bend sign. Public domain GIF files.
- Latex style file to provide a "danger" environment marked by a dangerous bend sign, based on Knuth's book.
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