\documentclass[12pt]{article}
\usepackage{amsfonts}

\voffset=-3.0cm
\hoffset=-2.6cm
\textwidth=17.5cm
\textheight=24cm

\renewcommand{\not}{\neg}
\renewcommand{\and}{\wedge}
\renewcommand{\or}{\vee}
\newcommand{\impl}{\Rightarrow}
\newcommand{\lequiv}{\Leftrightarrow} %equivalence as logical connective
\newcommand{\all}{\forall}
\newcommand{\exi}{\exists}
\newcommand{\elc}{\models}  % semantic logical consequence
\newcommand{\ylc}{\vdash}  % syntactic logical consequence
%\equiv is already defined for === semantic equivalence
\newcommand{\union}{\cup}
\newcommand{\intersect}{\cap}
\newcommand{\true}{{\mathbb{T}}}
\newcommand{\false}{{\mathbb{F}}}
\newcommand{\nov}[1]{{\overline{#1}}}

\pagestyle{empty}

\begin{document}

{\bf Logic 1, WS 2013.
Homework 8, given Dec 12, due Jan 09.}

\bigskip

\noindent
1.
In the development of the unification algorithm, study the cases ``constant -- constant'' and ``variable -- constant''.

\end{document}