# memoir headers with starred chapter

I need help with page layout in memoir. I want to have an unnumbered chapter0 (i.e. introduction) but when using the \chapter starred version the chapter headers is wrong. This is my example source:

\documentclass[14pt,extrafontsizes,a4paper,twoside,final]{memoir}
\usepackage[utf8]{inputenc}
\usepackage[italian]{babel}
\usepackage[T1]{fontenc}
\usepackage{indentfirst}
\usepackage{microtype}
\usepackage{lipsum}

\raggedbottomsection

\begin{document}
%
\OnehalfSpacing
%
\frontmatter
\thispagestyle{empty}
\begin{DoubleSpace}
\tableofcontents*
\end{DoubleSpace}
\clearforchapter

\mainmatter

\pagestyle{ruled}
\chapter*{chapter0}
\label{chap:chapter0}

\lipsum
\lipsum
\lipsum

\chapter{chapter1}
\label{chap:chapter1}

\section{ch1-s1}
\lipsum
\section{ch1-s2}
\lipsum
\section{ch1-s3}
\lipsum
\lipsum

\chapter*{last}
\label{chap:last}

\lipsum
\lipsum
\end{document}


And the problem is in chapter0 and in "last". Can you help me?

-

Use the optional argument provided for \chapter (works for \chapter* as well):

\chapter*[chapter0]{chapter0}


This will set the \chaptermark accordingly, and correct the headers. Why is this the case? Let's look at \@m@mschapter from memoir.cls:

\newcommand{\@m@mschapter}[2][\@empty]{%
\@schapter{#2}%
\ifx \@empty#1
\def\f@rhdr{#2}%
\else%                    opt arg
\def\f@rhdr{#1}%
\setcounter{secnumdepth}{-10}%
\chaptermark{#1}%
\setcounter{secnumdepth}{\value{maxsecnumdepth}}%
\fi
\ifanappendix
\memappchapstarinfo{\f@rhdr}{#2}%
\else
\memchapstarinfo{\f@rhdr}{#2}%
\fi

The optional argument is set to \@empty if not specified manually. Subsequently, the macro conditions on whether #1 (the optional argument) is \@empty or not, and specifying \chaptermark accordingly.
Note that using \label in an un-numbered sectional unit doesn't help.