The less than symbol(<) is a fundamental inequality symbol that many of us frequently use in mathematical contexts. It’s found on your keyboard, making it accessible for simple comparisons.
LaTeX allows for a wide variety of inequality symbols, combining the basic less than symbol with others.
This tutorial will guide you through the process of representing these symbols in LaTeX.
Below is a helpful table summarizing how the less than symbol is represented in LaTeX, its Unicode, the relevant LaTeX command, and the package (if any) required to use it:
Basic less than symbol in LaTeX
To represent the basic less than symbol in LaTeX, all you need is the default LaTeX command <. For example, to represent the inequality a < b, you can directly insert it into a LaTeX document as follows:
\documentclass{article}
\begin{document}
% You cannot directly use this symbol in text mode
\[ a < b \]
\[ p < q \]
\end{document}Output :
a < b p < q
Complex inequalities
In more complex mathematical equations, it is often necessary to represent relationships that involve more than just the basic less than symbol. For instance, you may want to show symbols like less than or equal to or other variations that combine the less than symbol with other mathematical notations.
To do this in LaTeX, you’ll need to import external packages, such as amssymb, which provides access to more advanced symbols.
\documentclass{article}
\usepackage{amssymb}
\begin{document}
\[ \leqslant \; \leqq \]
\[ \lessapprox \; \lesssim \]
\[ \lessdot \; \lesseqgtr \]
\[ \lessgtr \; \lesseqqgtr \]
\end{document}Output :
Not less than symbols
In some cases, you may need to express the opposite of the less than symbol, known as not less than. LaTeX makes this possible by negating the basic less than symbol.
Again, this requires the use of additional LaTeX commands or packages, such as amssymb.
\documentclass{article}
\usepackage{amssymb}
\begin{document}
\[ \nless \; \nleqq \]
\[ \nleqslant \; \nleq \]
\[ \lneqq \; \lneq \]
\[ \lnapprox \; \lnsim \]
\end{document}Output :
Best practices for much less than symbol
When dealing with inequalities that involve much smaller values, you might be tempted to use two less than symbols side by side (<<) to represent much less than.
However, this is not considered the best practice in LaTeX. Instead, the \ll command is preferred for professional and clean representation of this symbol.
\documentclass{article}
\usepackage{txfonts}
\begin{document}
\[ a << b \]
\[ p << q \]
\[ a \ll b \]
\[ p \nll q \]
\end{document}Output :
Summary
In this tutorial, we have covered the various ways to denote less-than-related symbols in LaTeX, from the basic less than symbol to more complex inequalities such as “less than or equal to” and “much less than.
Whether you are writing a simple equation or a more advanced mathematical proof, following these guidelines will ensure your LaTeX documents are both clear and professional. By adopting best practices, such as using \ll instead of <<.
