How to write a union symbol in LaTeX

This article aims to show you a simple way to create a union symbol in LaTeX.

In Mathematics you have the set operators, and sometimes when you are working with intervals or sets in math you may see the Union symbol. That’s why today you will learn how to insert it in your LaTeX document.

Union Symbol 

The union symbol is used in set theory, which represents one of the fundamental operations to combine two sets, known as union operation. If we have set A and set B, the union is defined as A U B, for example,

$$A\cup B=\{x\,:\, x \in A \text{ or } x \in B\}$$

Union Symbol in LaTeX

LaTeX has the standard union symbol built-in, it takes no value as argument, the command is \cup. 

\begin{document}
$$A \cup \left( B \cup C \right)$$
\end[document}

Of course we are not limited to just one size of the symbol, and we can adjust it a little bit more, adding maybe superscripts or subscripts, for other notations used in set theory, for example

\begin{document}
$$\cup_{i=1}^{n}S_{i}$$
\end[document}

Big Union symbol

You can also insert the union symbol using the command \bigcup, the output is a bigger symbol,

\begin{document}
$$\bigcup_{i=1}^{n}S_{i}$$
\end{document}

Another alternative to write the big union symbol along with the limits, is to use the command \limits before \bigcup, the output results in

\documentclass{article}\begin{document}
\begin{center}
    Set of natural numbers $\bigcup\limits_{i=1}^{\infty}A_{i}$
\end{center}
\end{document}

Notice that the command \bigcup\limits generated a smaller symbol than the command \bigcup. Personally I prefer the former option.

Lastly, there are some variations of the union symbols define as the disjoint union symbol, to generated them we have the following commands respectively,

\documentclass{article}\begin{center}
Disjoint union symbol
    $$A \sqcup B$$
    $$A \dot{\cup} B$$
    $$A \bigsqcup B$$
    $$A \uplus B$$
\end{center}

There could be packages that generated this symbol with other commands, but if you already have them by default use it already. 

Now you have the knowledge of the different types of union symbols out there, and how to insert them into your document. 

I hope you find this post useful and as always, keep writing in LaTeX.

Further Reading

LaTex Tutorial on Symbols

1. How To Create A Cross Product Symbol In LaTeX
2. How to create a hat symbol in LaTeX?
3. How to create a prime symbol in LaTeX?
4. How to create an absolute value symbol in LaTeX?
5. How to create an approximate symbol in LaTeX?
6. How to create an intersection symbol in LaTeX?
7. How to create the empty set symbol in LaTeX?
8. How to write a degree symbol in LaTeX?
9. How to write a dot product in LaTeX?
10. How to Write a Greater Than Symbol in LaTeX?
11. How to write a norm symbol in LaTeX?
12. How to write A Plus-Minus Symbol in LaTeX
13. How to write a proportional to symbol in LaTeX?
14. How to write a real number symbol in LaTeX?
15. How to write a tilde symbol in LaTeX?
16. How to write a vector in LaTeX?
17. How to write an infinity symbol in LaTeX?
18. How to write bold text in LaTeX?
19. How To Write Dots Symbols In LaTeX?
20. How to write the arrow symbols in LaTeX
21. How to write the Degree celsius symbol in LaTeX?
22. How to write the equal or not equal symbol in LaTeX?
23. How to write the Euro symbol in LaTeX?
24. How to write the floor symbol in LaTeX?
25. How to write the gradient operator symbol in LaTeX
26. How To Write The Greater Than Or Equal To Symbol In LaTeX?
27. How to write the integer number symbol in LaTeX?
28. How to write the less than symbol in LaTeX?
29. How to write the Natural numbers symbol in LaTeX?
30. How to write the parallel symbol in LaTeX?
31. How to write the percent symbol in LaTeX?
32. How to write the square root symbol in LaTeX?
33. How To Write The Symbol For A Subset In LaTeX?
34. How to write the symbol for therefore in LaTeX?
35. How to write with the mathbb in LaTeX?