\documentclass{article}

\usepackage{amssymb}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amsxtra}

\begin{document}




Please, replace this text with your abstract. Do not change the LaTeX
headers above, don't define any macros, don't create new sections, etc.
If your abstract compiles with LaTeX and looks good, then you can
copy-and-paste it into the registration form.
(Note: Copy the text between begin{document} and end{document},
do not include the LaTeX headers.)




\end{document}