The dangerous bend or caution symbol ☡ () was created by the

Nicolas Bourbaki Nicolas Bourbaki () is the collective pseudonym of a group of mathematicians, predominantly French alumni of the École normale supérieure (Paris), École normale supérieure (ENS). Founded in 1934–1935, the Bourbaki group originally intende ...

group of mathematicians and appears in the margins of

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

books written by the group. It resembles a

road sign Traffic signs or road signs are signs erected at the side of or above roads to give instructions or provide information to road users. The earliest signs were simple wooden or stone milestones. Later, signs with directional arms were introduc ...

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.

Variations

Others have used variations of the symbol in their books. The computer scientist

Donald Knuth Donald Ervin Knuth ( ; born January 10, 1938) is an American computer scientist and mathematician. He is a professor emeritus at Stanford University. He is the 1974 recipient of the ACM Turing Award, informally considered the Nobel Prize of comp ...

introduced an American-style road sign depiction in his Metafont and

TeX Tex, TeX, TEX, may refer to: People and fictional characters * Tex (nickname), a list of people and fictional characters with the nickname * Tex Earnhardt (1930–2020), U.S. businessman * Joe Tex (1933–1982), stage name of American soul singer ...

systems, with a pair of adjacent signs indicating doubly dangerous passages.

Typography

In the

LaTeX Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latices are found in nature, but synthetic latices are common as well. In nature, latex is found as a wikt:milky, milky fluid, which is present in 10% of all floweri ...

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

and then typing \dbend There are several variations given by \lhdbend, \reversedvideodbend, \textdbend, \textlhdbend, and \textreversedvideodbend.

In popular culture

The

Twenty One Pilots Twenty One Pilots is an American musical duo from Columbus, Ohio. Initially a band, the group was formed in 2009 by lead vocalist Tyler Joseph along with Nick Thomas and Chris Salih, who both left in 2011. Since their departure, the line-up h ...

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.

References

External links

Knuth's use of the dangerous bend sign. Public domain GIF files.
Mathematical symbols * Symbols introduced in the 20th century {{Visual-symbol-stub

Variations

Typography

In popular culture

See also

References

External links