Bourbaki dangerous bend symbol: Difference between revisions
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{{Short description|Typological symbol representing difficulty}} |
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[[File:Borne_Michelin_Virages.JPG|thumb|French "{{lang|fr|virages dangereux}}" road sign, before 1949]] |
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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 |
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''' 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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{{clear}} |
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==Typography== |
==Typography== |
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\begin{ddanger} ... \end{ddanger}.</pre> This requires LaTeX3. [http://texnicalstuff.blogspot.com/2009/08/latex-macros.html]. |
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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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There are several variations given by <code>\lhdbend</code>, <code>\reversedvideodbend</code>, <code>\textdbend</code>, <code>\textlhdbend</code>, and <code>\textreversedvideodbend</code>. |
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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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*[http://www.truetex.com/db.htm Knuth's use of the dangerous bend sign. Public domain GIF files.] |
*[http://www.truetex.com/db.htm Knuth's use of the dangerous bend sign. Public domain GIF files.] |
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*[http://texnicalstuff.blogspot.com/2009/08/latex-macros.html Latex style file to provide a "danger" environment marked by a dangerous bend sign, based on Knuth's book.] |
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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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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
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
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
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
References
- ^ 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
- 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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