math-mode
I would like to put a vertical bar in my regex expression but I keep getting an error when I put in \mid. Can you help?
\item \textbf{Give a regular expression for the language accepted by the automaton~$A$.} \\\\
(0 \mid 1)*01)0 \mid 1)*\\
\item \textbf{Explain what makes the automaton~$A$ non-deterministic.}\\\\
The reason automaton~$A$ is non-deterministic is because in the state q0 reading a 0 can either lead to $q_0$ or $q_1$.
The ligature ö consists of \"{o}, which can happen in text but not math mode. Here's how it should be used:
\documentclass{article}
\usepackage[utf8]{inputenc}% http://ctan.org/pkg/inputenc
\usepackage{amsmath}% http://ctan.org/pkg/amsmath
\begin{document}
\begin{equation}
\Delta x = x_\text{efter} - x_\text{före} \label{eq:difference}
\end{equation}
\end{document}
amsmath provides \text{<stuff>} which prints <stuff> in text mode. inputenc allows you to specify ligature as-is in your code.
As a side-note, it's best to label things with descriptive names.
You're not consistent with delimiting math formulas; for instance, in the second \STATE line, you open a math formula, without closing it.
I have tried to make the algorithms more consistent. Note that \LOOP and \Loop are not the same (and the latter is not defined in algorithmic). If you're using a different set of packages, please make it known.
\documentclass{article}
\usepackage{amsmath}
\usepackage{algorithm}
\usepackage{algorithmic}
\newcommand{\kw}[1]{\textrm{#1}}
\begin{document}
\begin{algorithm}
\caption{Algorithme de Dijkstra}
\begin{algorithmic}[1]
\REQUIRE Un graphe $G$
\REQUIRE Un noeud source $s$
\ENSURE Les plus court chemins de $s$ vers tout les autres noeuds de $G$ $A$
\FORALL{$v \in V[G]$}
\STATE $d[v] \leftarrow +\infty$
\STATE $\kw{previous}[v] \leftarrow \kw{undefined}$
\ENDFOR
\STATE $d[s] \leftarrow 0$
\STATE $S \leftarrow \kw{empty set}$
\STATE $Q \leftarrow V[G]$
\LOOP
\STATE $Q$ is not an empty set
\STATE $u \leftarrow \kw{Extract}_{\kw{Min}}(Q)$
\STATE $S \leftarrow S \cup \{u\}$
\FORALL{edge $(u,v)$ outgoing from $u$}
\IF{$d[u] + w(u,v) < d[v]$}
\STATE $d[v] \leftarrow d[u] + w(u,v)$
\STATE $\kw{previous}[v] := u$
\ENDIF
\ENDFOR
\ENDLOOP
\end{algorithmic}
\end{algorithm}
\end{document}
Best Answer
\midcauses tex to switch into math mode, and it's still in math mode when it gets to the next\item, hence the unexpected error message.instead of what you have, make the line with
\midan unnumbered math display:using double backslashes, as already commented, is not a good practice. see When to use \par and when
\\for more information.edit: based on a comment about what is math and what isn't, i've adjusted the original code; i've also applied my "editing pencil" to the position of "either" for clarity. (apologies for my presumption; see my user profile to understand why i'm fussy this way.)