1

I don't know why this code doesn't work:

\documentclass[11pt]{article}
\usepackage{fullpage}
\usepackage{amsfonts}
\usepackage[utf8]{inputenc}
\usepackage{amsthm}
\newtheorem{theorem}{Teorema}
\theoremstyle{definition}
\newtheorem{definition}{Definição}
\begin{document}

\begin{definition}

Um conjunto $H$ com uma operação binária associativa é chamado de semigrupo.

\end{definition}

\begin{definition}

Um semigrupo $H\subset \mathbb{N}$ é chamado de numérico quando $0\in H$, $L=\mathbb{N}-H$ é finito e $1\in L$. Os elementos $1=l_1\lt l_2\ldots\lt l_g$ de $L$ são chamados de lacunas de $H$ e os elementos $0=n_0\lt n_1\lt\ldots$ de $H$ são chamados de não-lacunas de $H$. A quantidade de lacunas de $H$ é chamada de gênero de $H$.

\end{definition}

\begin{definition}

Um semigrupo numérico $H$ é chamado de hiperelíptico quando $n_1=2\in H$.

\end{definition}

\end{document}

Log:

! Undefined control sequence.
l.19 ... finito e $1\in L$. Os elementos $1=l_1\lt
l_2\ldots\lt l_g$ de $L$ ...
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.
! Undefined control sequence.
l.19 ...in L$. Os elementos $1=l_1\lt l_2\ldots\lt
l_g$ de $L$ são chamados...

It's something to do with the language?

Thanks

user108205
  • 113
  • There is no \lt command as far as I know. Use < instead if you mean that symbol. –  Sep 19 '14 at 04:09
  • At several places \lt is used inside math. What it is supposed to mean? – Heiko Oberdiek Sep 19 '14 at 04:10
  • 1
    See http://tex.stackexchange.com/questions/12519/what-library-do-i-have-to-use-such-that-the-document-can-render-lt-and-gt-as-l – Adam Liter Sep 19 '14 at 04:10
  • @user108205: I retagged your question, since it's not connected to languages but to an error due to an unknown macro named \lt –  Sep 19 '14 at 04:29
  • @user108205 One doubt: o/ If you write in Portuguese why don't you load the babel or the polyglossia packages? – Aradnix Sep 19 '14 at 06:43
  • @Aradnix What are the advantages of these packages? – user108205 Sep 21 '14 at 12:49
  • Well when you use them you don't need to translate manually the hierarchy macros such as chapter, section, tableofcontents, etc. Also gives you the right hyphenation according the rules of your language instead of the English. They are also helpful with the decimal marker you use. – Aradnix Sep 22 '14 at 00:23
  • @user108205 Also it helps you to improve your references if you use also biblatex. – Aradnix Sep 23 '14 at 04:49
  • 1
    @Aradnix Thank you very much, I didn't know it! – user108205 Sep 23 '14 at 20:31

1 Answers1

1

I think, \lt should mean less than, there is no such command however, as far as I know.

It's easy to define such a command with this meaning, if needed:

\newcommand{\lt}{\ensuremath{<}}%

There are some commands called \le and \ge meaning <= etc.

In addition, if needed, a \gt can be defined accordingly:

\newcommand{\gt}{\ensuremath{>}}%

\documentclass[11pt]{article}
\usepackage{fullpage}
\usepackage{amsfonts}
\usepackage[utf8]{inputenc}
\usepackage{amsthm}
\newtheorem{theorem}{Teorema}
\theoremstyle{definition}
\newtheorem{definition}{Definição}

\newcommand{\lt}{\ensuremath{<}}%
\begin{document}

\begin{definition}

Um conjunto $H$ com uma operação binária associativa é chamado de semigrupo.

\end{definition}

\begin{definition}

Um semigrupo $H\subset \mathbb{N}$ é chamado de numérico quando $0\in H$, $L=\mathbb{N}-H$ é finito e $1\in L$. Os elementos $1=l_1 \lt l_2\ldots \lt l_g$ de $L$ são chamados de lacunas de $H$ e os elementos $0=n_0\lt n_1\lt\ldots$ de $H$ são chamados de não-lacunas de $H$. A quantidade de lacunas de $H$ é chamada de gênero de $H$.

\end{definition}

\begin{definition}

Um semigrupo numérico $H$ é chamado de hiperelíptico quando $n_1=2\in H$.

\end{definition}

\end{document}