In discussions of Sobolev spaces one often sees the Japanese bracket, $$\langle x \rangle = (1+|x|^2)^{1/2},$$ as useful shorthand.

I was not easily able to find information about this term.

(1) What was the first systematic usage of something like this shorthand?

(2) What is the origin of the specific phrase "Japanese bracket"?

(3) Why is it called the "Japanese bracket"? The answer to this may be obvious from the answers to either (1) or (2).


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.