🌐
Software Accountant
softwareaccountant.com › type-empty-set-symbol-text
Ø | How to Type Empty Set Symbol Text In Word, Windows, & Mac (On Keyboard) - Software Accountant
March 3, 2024 - Kindly click on it to insert it into your text. These are the steps you may use to insert this and any other symbol on Mac using the Character Viewer. MS Word shortcut to type the Empty Set Symbol is 2205, Alt + X.
🌐
PC Review
pcreview.co.uk › newsgroups › microsoft word › microsoft word document management
How do I make a "null sign?" | PC Review
March 28, 2007 - N U L ... which is U+2400 (press and hold Alt while you type 9216 - or in recent versions of Word type 2400 and press Alt+X) ... Hi Tony, The NUL character is from a completely different field, telecommunications (along with characters such as ACK and BEL). While a "null symbol" may not literally exist, there is a symbol for the mathematical concept of a "null set" or "empty set".
🌐
Google Groups
groups.google.com › g › microsoft.public.word.docmanagement › c › RoU44o7OwQM
Re: How do I make a "null sign?"
While a "null symbol" may not literally exist, there is a symbol for the mathematical concept of a "null set" or "empty set". It's in the Arial Unicode MS font as character 2205. And, contrary to Ed G's statement earlier, it is not a zero with a vertical slash, it's a circle with a diagonal slash.
🌐
YouTube
youtube.com › vishap tvplus
How to type Empty Set symbol in Word - YouTube
https://www.youtube.com/channel/UCmV5uZQcAXUW7s4j7rM0POg?sub_confirmation=1 How to type Empty Set symbol in Word
Published   April 24, 2020
Views   1K
🌐
YouTube
youtube.com › watch
How to type empty set or null set symbol in word - Shortcuts and Alt codes for empty set symbol - YouTube
4 ways to make an empty ty set symbol in Microsoft word:1. Keyboard Short keys2. Alt Code3. Symbol Library4. Copy and Paste
Published   December 9, 2022
🌐
How to Type Anything
howtotypeanything.com › type-empty-set-symbol
Ø | How to Type Empty Set Symbol on Keyboard - How to Type Anything
April 27, 2021 - For Windows users, press down the Alt key and type 0216 using the numeric keypad, then release the Alt key. These shortcuts work in both Microsoft Word, Excel, and PowerPoint and anywhere on the Windows or Mac PC.
🌐
Symbol Hippo
symbolhippo.com › home › ø | empty set symbol (meaning, how to type on keyboard, & more)
Ø | Empty Set Symbol (Meaning, How To Type on Keyboard, & More) - Symbol Hippo
January 23, 2022 - Empty Set or Null set symbol (Ø) is a mathematical symbol used to indicate a unique set that has no elements. It is denoted by O with a forward slash.
Find elsewhere
🌐
Mathematics Monster
mathematics-monster.com › symbols › Empty-Set.html
The "Empty Set (∅)" Symbol
On the assumption that you already have your canvas and the context set up, use the Hex code in the format 0x2205 to place the ∅ symbol on your canvas. For example: (Method 7) Use the Unicode (for various, e.g. Microsoft Office, JavaScript, Perl). The Unicode for ∅ is U+2205. The important part is the hexadecimal number after the U+, which is used in various formats. For example, in Microsoft Office applications (e.g. Word, PowerPoint), do the following:
🌐
Alt Code List
altcodeunicode.com › home › alt codes for math set membership signs (∌ ∅ ∈)
Alt Codes for Math Set Membership Signs (∌ ∈ & More) | Keyboard Shortcuts
July 7, 2024 - How to easily type mathematical set membership signs (∌ ∅ ∈) using Windows Alt codes. Or click any set membership sign to copy and paste into your document.
🌐
Cyber Definitions
cyberdefinitions.com › symbols › mathematics-symbols › Empty-Set.html
'Empty-Set' | Symbol and Codes
Press the "Copy" button, and then paste the symbol into your document. The Alt Code for ∅ is Alt 8709. If you have a keyboard with a numeric pad, you can use this method. Simply hold down the Alt Key and type 8709.
Top answer
1 of 2
33

I would say the following should be not too controversial:

  • $\emptyset$ and $\varnothing$ are typographical variants of the same mathematical symbol designating the empty set

  • The symbol was introduced by Bourbaki, was inspired by the Norwegian character Ø, but is a distinct character from it

  • The intention was most probably to create a symbol related to $0$ (zero), not to O (Oh), distinguished from it by striking it through. After all the empty set has all kinds of relations with the number $0$, but none with the letter O. (By contrast big-Oh and little-o symbols derive from the word "order".)

  • The symbol has absolutely no relation (apart from appearance) with the lower-case Greek letter phi, with typographical variants $\phi$ and $\varphi$.

2 of 2
22

There is a webpage where you can find mention of this: http://jeff560.tripod.com/set.html

Here's an extract

The null set symbol (Ø) first appeared in N. Bourbaki Éléments de mathématique Fasc.1: Les structures fondamentales de l'analyse; Liv.1: Theorie de ensembles. (Fascicule de resultants) (1939): "certaines propriétés... ne sont vraies pour aucun élément de E... la partie qu’elles définissent est appelée la partie vide de E, et designée par la notation Ø." (p. 4.)

André Weil (1906-1998) says in his autobiography that he was responsible for the symbol:

Wisely, we had decided to publish an installment establishing the system of notation for set theory, rather than wait for the detailed treatment that was to follow: it was high time to fix these notations once and for all, and indeed the ones we proposed, which introduced a number of modifications to the notations previously in use, met with general approval. Much later, my own part in these discussions earned me the respect of my daughter Nicolette, when she learned the symbol Ø for the empty set at school and I told her that I had been personally responsible for its adoption. The symbol came from the Norwegian alphabet, with which I alone among the Bourbaki group was familiar.

The citation above is from page 114 of André Weil's The Apprenticeship of a Mathematician, Birkhaeuser Verlag, Basel-Boston-Berlin, 1992. Translated from the French by Jennifer Gage. The citation was provided by Julio González Cabillón.

You should also note that Nicolas Bourbaki is a collective pseudonym for a group of French-speaking mathematicians.

Concerning your question, I remember one of my math professor telling us that in fact, it was a claim by both André Weil and Claude Chevalley, but I can't find the citation for Chevalley.


I've found also this lecture about history of math from a Canadian University (in French), where this issue is mentioned: http://www.mat.ulaval.ca/fileadmin/Cours/MAT-2500/Bourbaki.pdf

🌐
Quora
quora.com › What-is-the-name-of-the-symbol-used-for-expressing-empty-sets
What is the name of the symbol used for expressing empty sets? - Quora
Answer: It’s called the “empty set symbol.” I wish I could give you some cool name like “octothorpe”, but it was based on the letter Ø from Danish, where it is a Close-mid front rounded vowel and “the name of this letter is the same as the sound it represents” [1]. The first ...
🌐
Wikipedia
en.wikipedia.org › wiki › Null_symbol
Null symbol - Wikipedia
June 28, 2025 - Look up null or ␀ in Wiktionary, the free dictionary. Null symbol may refer to: Null character, U+0000 <control-0000> , Null sign (∅), the empty set · Null (SQL) (ω), a special marker and keyword NULL in SQL · Empty string (λ, Λ, or ε), in formal language theory ·
🌐
Minnesota State University
web.mnstate.edu › peil › MDEV102 › U1 › S2 › SetTerms4.htm
Element, Equal, Empty Set
Notation: The symbol ∈ is used ... is a state bordering Minnesota}, Iowa ∈ S, but Alabama ∉ S. Empty Set: The empty set (or null set) is a set that has no members....
🌐
Wikipedia
en.wikipedia.org › wiki › Null_sign
Null sign - Wikipedia
June 13, 2025 - Common notations for the empty set include "{}", "∅", and " ... {\displaystyle \emptyset } ". The latter two symbols were introduced by the Bourbaki group (specifically André Weil) in 1939, inspired by the letter Ø in the Danish and Norwegian ...
🌐
Wikipedia
en.wikipedia.org › wiki › Empty_set
Empty set - Wikipedia
3 days ago - However, null set is a distinct notion within the context of measure theory, in which it describes a set of measure zero (which is not necessarily empty). Common notations for the empty set include "{ }", " ... {\displaystyle \emptyset } ", and "∅". The latter two symbols were introduced by the Bourbaki group (specifically André Weil) in 1939, inspired by the letter Ø (U+00D8 Ø LATIN CAPITAL LETTER O WITH STROKE) in the Danish and Norwegian alphabets.