everybody. I need to customize the proof name as "Demostración" underlined and with a linebreak after that proof name. I have tried with these codes. I'm going to tell you what I got with each one and what I couldn't get.
\renewcommand{\proofname}{\bfseries \underline{Demostración} \newline}
With this one I couldn't underline the proofname nor the linebreak, but \qedhere works perfectly.
\renewenvironment{proof}{{\it \underline{Demostración} \newline}}{\qed}
With this second one I could underline the proof name and get the linebreak, but \qedhere doesn't work with lists (\enumerate or \itemize environments).
\makeatletter
\renewenvironment{proof}[1][\proofname] {\par\pushQED{\qed}\normalfont \topsep6\p@\@plus6\p@\relax\trivlist\item[\hskip\labelsep\it\underline{#1}%
\@addpunct{}\newline]\ignorespaces}{\popQED\endtrivlist\@endpefalse}
\makeatother
With this last one I couldn't get the underlined proof name, nor the linebreak, but \qedhere works perfctly.
What else can I do in order to customize the \proof environmen as I need?
Thanks for your help.
ntheorem, you have this theorem style pre-defined (nonumberbreak). – Bernard Jul 27 '17 at 02:05