I want to show identity element of a normed vector space with 1 that have extra line .How can I do it?

  • In order for your question to not get closed as being unclear. Please explain in more detail what you are looking for. As the question is here is is hard to understand what you are talking about.
    – daleif
    Dec 6, 2022 at 12:00
  • @Sigur - Which math font package provides usable output for \mathbb{1}?
    – Mico
    Dec 6, 2022 at 12:30
  • 1
    @Mico, sorry. I mean ds as you wrote. It was out of habit. lol
    – Sigur
    Dec 6, 2022 at 12:49
  • 1
    Normed vector space don't have a 1. Normed algebras may.
    – egreg
    Dec 6, 2022 at 14:13

1 Answer 1


If by "1 that have extra line" you mean a double-struck 1, the following solution may be of interest to you.

enter image description here

\documentclass{article} % or some other suitable document class
  • Thanks a lot. It works for me. Dec 6, 2022 at 12:57

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