Bourbaki dangerous bend symbol
Encyclopedia
The dangerous bend or caution symbol ☡ (unicode
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.
Others have used variations of the symbol in their textbooks, and computer scientist Donald Knuth
introduced a more realistic road-sign depiction in his Metafont
and TeX
systems, with a pair of adjacent signs indicating doubly dangerous passages.
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
and then typing
There are several variations given by \lhdbend, \reversedvideodbend, \textdbend, \textlhdbend,
and \textreversedvideodbend.
Unicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
U+2621, "CAUTION SIGN") was created by the Nicolas Bourbaki
Nicolas Bourbaki
Nicolas Bourbaki is the collective pseudonym under which a group of 20th-century mathematicians wrote a series of books presenting an exposition of modern advanced mathematics, beginning in 1935. With the goal of founding all of mathematics on set theory, the group strove for rigour and generality...
group of mathematicians and appears in the margins of mathematics
Mathematics
Mathematics is the study of quantity, space, structure, and change. Mathematicians seek out patterns and formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proofs, which are arguments sufficient to convince other mathematicians of their validity...
books written by the group. It resembles a road sign
Traffic sign
Traffic signs or road signs are signs erected at the side of roads to provide information to road users. With traffic volumes increasing over the last eight decades, many countries have adopted pictorial signs or otherwise simplified and standardized their signs to facilitate international travel...
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.
Others have used variations of the symbol in their textbooks, and computer scientist Donald Knuth
Donald Knuth
Donald Ervin Knuth is a computer scientist and Professor Emeritus at Stanford University.He is the author of the seminal multi-volume work The Art of Computer Programming. Knuth has been called the "father" of the analysis of algorithms...
introduced a more realistic road-sign depiction in his Metafont
METAFONT
Metafont is a programming language used to define vector fonts. It is also the name of the interpreter that executes Metafont code, generating the bitmap fonts that can be embedded into e.g. PostScript...
and TeX
TeX
TeX is a typesetting system designed and mostly written by Donald Knuth and released in 1978. Within the typesetting system, its name is formatted as ....
systems, with a pair of adjacent signs indicating doubly dangerous passages.
Typography
In HTML the unicode dangerous bend symbol ☡ can be produced by:- ☡
In the LaTeX
LaTeX
LaTeX is a document markup language and document preparation system for the TeX typesetting program. Within the typesetting system, its name is styled as . The term LaTeX refers only to the language in which documents are written, not to the editor used to write those documents. In order to...
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.