\documentclass[DIV14,12pt,a4paper,pagesize,headsepline]{scrreprt}
\setlength\parindent{0pt}
\addtolength{\parskip}{\baselineskip}

\usepackage[automark]{scrpage2}

\renewcommand*{\chapterformat}[0]{%
  \makebox[0pt][r]{\thechapter\autodot\enskip}}

\usepackage[normalem]{ulem}
% \usepackage{sectsty}

\usepackage{enumerate}

\usepackage{ae}
\usepackage[T1]{fontenc}
% \usepackage[latin1]{inputenc}
% \usepackage{ucs}
\usepackage[utf8x]{inputenc}
\usepackage{ngerman}

\usepackage{listings}
\usepackage[normalem]{ulem}

\makeatletter
\providecommand{\pmatr}[1]{\begin{pmatrix}#1\end{pmatrix}}
\providecommand{\matr}[1]{\begin{matrix}#1\end{matrix}}
\providecommand{\wrap}[1]{\langle#1\rangle}
\providecommand{\affin}[0]{\mathbb{A}}
\providecommand{\set}[1]{\left\{#1\right\}}
\providecommand{\proj}[0]{\mathbb{P}}
\providecommand{\projh}[1]{\wrap{#1}_\text{proj}}
\providecommand{\without}[0]{\backslash}
\providecommand{\withoutnull}[0]{\without \set{0}}

\providecommand{\Los}[0]{\mathbb{L}}
\providecommand{\Q}[0]{\mathbb{Q}}
\providecommand{\R}[0]{\mathbb{R}}
\providecommand{\C}[0]{\mathbb{C}}
\providecommand{\N}[0]{\mathbb{N}}
\providecommand{\Z}[0]{\mathbb{Z}}
\providecommand{\F}[0]{\mathbb{F}}
\providecommand{\cO}[0]{\mathcal{O}}
\providecommand{\cA}[0]{\mathcal{A}}
\providecommand{\cB}[0]{\mathcal{B}}
\providecommand{\cC}[0]{\mathcal{C}}
\providecommand{\cD}[0]{\mathcal{D}}
\providecommand{\cF}[0]{\mathcal{F}}
\providecommand{\cG}[0]{\mathcal{G}}
\providecommand{\cR}[0]{\mathcal{R}}
\providecommand{\cM}[0]{\mathcal{M}}
\providecommand{\cL}[0]{\mathcal{L}}
\providecommand{\cK}[0]{\mathcal{K}}
\providecommand{\cS}[0]{\mathcal{S}}
\providecommand{\cT}[0]{\mathcal{T}}
\providecommand{\cU}[0]{\mathcal{U}}
\providecommand{\cV}[0]{\mathcal{V}}

\providecommand{\abs}[1]{\lvert#1\rvert}
\providecommand{\norm}[1]{\lVert#1\rVert}
\providecommand{\ceil}[1]{\lceil#1\rceil}

\def\partname\@empty

\def\thechapter{\Roman{chapter}}
\renewcommand\thechapter{\Roman{chapter}}

\def\thesection{\arabic{section}}
\renewcommand\thesection{\arabic{section}}
\def\thesubsection{\alph{subsection})}
\renewcommand\thesubsection{\alph{subsection})}

\chead{\leftmark}

\makeatother

\usepackage{graphicx}						%Paket für Grafikeinbindung

\usepackage{amssymb}
\usepackage[sumlimits,intlimits,namelimits]{amsmath}
\usepackage{amsthm}   % erweiterte Theorem-Umgebungen
\usepackage{amscd}

\DeclareMathOperator{\Kern}{Kern}
\DeclareMathOperator{\Bild}{Bild}
\DeclareMathOperator{\im}{im}
\DeclareMathOperator{\id}{id}
\DeclareMathOperator{\grad}{grad}
\DeclareMathOperator{\rang}{rang}
\DeclareMathOperator{\Bil}{Bil}
\DeclareMathOperator{\Char}{char}
\DeclareMathOperator{\Hom}{Hom}
\DeclareMathOperator{\Aut}{Aut}
\DeclareMathOperator{\Inn}{Inn}
\DeclareMathOperator{\Out}{Out}
\DeclareMathOperator{\End}{End}
\DeclareMathOperator{\Stab}{Stab}
\DeclareMathOperator{\GL}{GL}
\DeclareMathOperator{\PGL}{PGL}
\DeclareMathOperator{\SL}{SL}
\DeclareMathOperator{\PSL}{PSL}
\DeclareMathOperator{\GF}{GF}
\DeclareMathOperator{\sign}{sign}
\DeclareMathOperator{\Syl}{Syl}
\DeclareMathOperator{\Mod}{mod}
\DeclareMathOperator{\Ind}{Ind}
\DeclareMathOperator{\Res}{Res}
\DeclareMathOperator{\Irr}{Irr}
\DeclareMathOperator{\tr}{tr} % Spur
\DeclareMathOperator{\Cl}{Cl}
\DeclareMathOperator{\Inf}{Inf} % Inflation Funktor
\DeclareMathOperator{\Obj}{Obj}
\DeclareMathOperator{\Ab}{Ab}
\DeclareMathOperator{\opp}{opp}
\DeclareMathOperator{\coker}{coker}


\DeclareMathOperator{\Reid}{Reid}
\DeclareMathOperator{\Liid}{Liid}


%%
%% Index-Erstellung
%%
%\usepackage{makeidx}
%\makeindex            % damit eine Indexdatei angelegt wird

%%
%% XY-Pic für Diagramme etc
%%
\usepackage[all]{xy}      % Das Paket mit allem, was man so braucht
%\UseComputerModernTips    % Pfeilspitzen wie im normalen Mathe-Modus
%\CompileMatrices          % Damit geht es etwas schneller.


\usepackage{mathrsfs}  % gibt den Befehl "\mathscr{}" für schöne
                       % Mathe-Skript-Buchstaben 


%Satz/Lemma/... Definitionen

\newtheoremstyle{mystyle}% name
  {3pt}%      Space above
  {3pt}%      Space below
  {}%         Body font
  {}%         Indent amount (empty = no indent, \parindent = para indent)
  {\bfseries}% Thm head font
   {:}%        Punctuation after thm head
   { }%     Space after thm head: " " = normal interword space;
         %       \newline = linebreak
  {}%         Thm head spec (can be left empty, meaning `normal')

\theoremstyle{mystyle}
\newtheorem{tsatz}{Satz}[section]
% \newtheorem{tdefinition}[tsatz]{Definition}
\newtheorem{tlemma}[tsatz]{Lemma}
\newtheorem{tprop}[tsatz]{Proposition}
\newtheorem{tkorr}[tsatz]{Korrolar}

\makeatletter

\def\thetsatz{\arabic{chapter}\ifnum\value{section}>0 .\arabic{section}\fi .\arabic{tsatz}}
\renewcommand\thetsatz{1.\arabic{chapter}\ifnum\value{section}>0 .\arabic{section}\fi .\arabic{tsatz}}
\newenvironment{satz}[1][]{\begin{tsatz}[#1]\hypertarget{satz.\thetsatz}{}}{\end{tsatz}}
% \newenvironment{definition}[1][]{\begin{tdefinition}[#1]\hypertarget{satz.\thetsatz}{}}{\end{tdefinition}}
\newenvironment{lemma}[1][]{\begin{tlemma}[#1]\hypertarget{satz.\thetsatz}{}}{\end{tlemma}}
\newenvironment{prop}[1][]{\begin{tprop}[#1]\hypertarget{satz.\thetsatz}{}}{\end{tprop}}
\newenvironment{korr}[1][]{\begin{tkorr}[#1]\hypertarget{satz.\thetsatz}{}}{\end{tkorr}}

\providecommand{\hl}{\hyperlink}

\providecommand{\tocsection}[1]{\section*{#1}\addcontentsline{toc}{section}{#1}}

\providecommand{\Rightarrowstar}[0]{\mathop{\Longrightarrow}\limits^{*}}
\providecommand{\Rightarrowleq}[1]{\mathop{\Longrightarrow}\limits^{\leq{#1}}}
\providecommand{\Leftrightarrowstar}[0]{\mathop{\Longleftrightarrow}\limits^{*}}

\makeatother

\theoremstyle{mystyle}
\newtheorem*{definition}{Definition}
\theoremstyle{remark}
\newtheorem*{bem}{Bemerkung}
\newtheorem*{bsp}{Beispiel}

\newenvironment{bew}{\begin{proof}[Beweis]}{\end{proof}}

\usepackage[colorlinks]{hyperref}

\pagestyle{scrheadings}