NullGraph 2002-06-24 19:38:14 2005-06-29 12:34:38 Definition % this is the default PlanetMath preamble. as your knowledge % of TeX increases, you will probably want to edit this, but % it should be fine as is for beginners. % almost certainly you want these \usepackage{amssymb} \usepackage{amsmath} \usepackage{amsfonts} % used for TeXing text within eps files \usepackage{psfrag} % need this for including graphics (\includegraphics) \usepackage{graphicx} % for neatly defining theorems and propositions %\usepackage{amsthm} % making logically defined graphics %\usepackage{xypic} % there are many more packages, add them here as you need them % define commands here The null graph is the graph with no vertices or edges. The null graph is the initial object in the category of graphs. {\bf Further Reading} \begin{itemize} \item Harary, F. and Read, R. ``Is the null-graph a pointless concept?'', Lecture Notes in Mathematics 406 (1974), pp. 37-44. \end{itemize}