I'm using variables `u`

, `v`

, `w`

in a lemma. However my latex compiler changes `v`

to `υ`

which then makes it difficult to distinguish between `u`

and `υ`

.

Why does it do this and how can I avoid it from happening?

I'm following the simple lemma format:

```
\begin{lemma}
\end{lemma}
\begin{proof}
\end{proof}
```

EDIT:

After David's comment, I simplified my document to point out the problem:

```
\documentclass{article}
\usepackage[utf8]{inputenc}
\title{s}
\author{author}
\date{November 2014}
\newtheorem{theorem}{Theorem}[section]
\newtheorem{corollary}{Corollary}[theorem]
\newtheorem{lemma}[theorem]{Lemma}
\begin{document}
\maketitle
\section{Introduction}
\begin{lemma}
Let $u$, $v$, $w$
\label{lemma4}
\end{lemma}
\end{document}
```

## Best Answer

the "curly" form of "v" has long been standard in mathematical typesetting to distinguish it from the greek "nu". the "w" is also changed for consistent style.

i've simplified your example a bit and added instances of nu and upsilon to show the difference.

it is essential in math that each letter be recognizable

by itself, with no additional context, to avoid misinterpretation. math fonts are specially designed precisely for this reason. (this is also the reason why many uppercase greek letters are not supported by tex -- because the shapes are identical to those in the latin alphabet.)