```
\documentclass{beamer}
\usepackage[all]{xy}
\begin{document}
\section{Introduction}
\xymatrix{
&*+{\sum_{i=n}^m {i^2}} &*+{+}&*+{p} \\
& {\bullet} & D \ar[ul] && f \ar[ul]
}
\end{document}

```

i want to reduce the spacing between terms and different colors for arrows.i'm using kile under ubuntu.is it necessary to include tiKZ ,if so explain me