Iverson bracket

An Iverson bracket (sometimes called a "was it asked?" bracket) is a type of punctuation used to show that when you read something, you should think carefully about if it was actually asked. It looks like this: [...?]. It is named after the mathematician Richard Iverson, who used it often.

Imagine your teacher tells you to solve a math problem. To make sure you understand what kind of problem it is, your teacher might put an Iverson bracket after the question. This tells you to really think about if the question is something you need to answer, or if it's just an example of something else.