Bourbaki harmful bend image – Wikipedia

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Typological image representing problem
The harmful bend or warning image ☡ (U+2621 ☡ CAUTION SIGN) was created by the Nicolas Bourbaki group of mathematicians and seems within the margins of mathematics books written by the group. It resembles a road sign that signifies a “harmful bend” within the street forward, and is used to mark passages tough on a primary studying or with an particularly troublesome 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 in opposition to critical errors, the place he dangers falling; these passages are indicated within the margin with the signal ☡ (“harmful bend”)
Nicolas Bourbaki’s description of the image in a number of textbooks[2]
Variations[edit]
Others have used variations of the image of their books. The pc scientist Donald Knuth launched an American-style road-sign depiction in his Metafont and TeX techniques, with a pair of adjoining indicators indicating doubly harmful passages.[3][4][5][6]
Typography[edit]

Within the LaTeX typesetting system, Knuth’s harmful bend image could be produced by
first loading the font manfnt (a font with additional symbols utilized in Knuth’s TeX guide) with
usepackage{manfnt}
after which typing
dbend
There are a number of variations given by lhdbend
, reversedvideodbend
, textdbend
, textlhdbend
, and textreversedvideodbend
.
See additionally[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 instance, 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 College Press, ISBN 0-521-75374-0, p. xiv.
- ^ Gerard P. Michon (2012), Dangerous Bend Symbol, doubled and tripled, Numericana.
Exterior hyperlinks[edit]