Bourbaki dangerous bend symbol

From Wikipedia, the free encyclopedia

The dangerous bend symbol was created by the Nicolas Bourbaki group of mathematicians and appears in the margins of mathematics books written by the group. It looks like a street 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, including computer scientist Donald Knuth, used the symbol in their textbooks.

[edit] References

• Knuth's use of the dangerous bend sign. Public domain GIF files.

[edit] See also

• Halmos box