I wanted to draw
Remark: The numbers on the diagram are not the part of the code. They show the sequence of precedence of the moving arrow.
MWE by editing this code:
\documentclass{beamer}
\usepackage[latin1]{inputenc}
\usepackage{times}
\usepackage{tikz}
\usepackage{verbatim}
\usetikzlibrary{arrows,shapes}
\begin{document}
\begin{frame}
\frametitle{flowchart}
\tikzstyle{format} = [draw, thin, fill=green]
\tikzstyle{form} = [draw, thin, fill=yellow]
\tikzstyle{med} = [draw, thin, fill=red]
\begin{figure}
\begin{tikzpicture}[node distance=3cm, auto,>=latex', thick]
\path[use as bounding box] (-1,0) rectangle (10,-2);
\path[->]<1-> node[format] (a1) {$A_1$};
\path[->]<2-> node[form, right of=dvi] (ps) {$A_2$}
node[format, below of=dvi] (b1) {$B_1$}
(a1) edge node {$\beta$} (ps);
\path[->]<3-> node[med, right of=ps] (b2) {$A_3$}
node[med, below of=ps] (b3) {$B_2$}
(b1) edge node {$\alpha$} (b3)
(ps) edge node {$\gamma$} (b2)
edge node[swap] {$\delta$} (b1)
edge (b3);
\path[<-]<4-> (a1) edge node {$\delta$} (b3);
\path[<-, draw]<5-> (a1) -- +(0,1) -| node[near start] {$\lambda$} (b2);
\end{tikzpicture}
\end{figure}
\end{frame}
\end{document}


figureenvironment is rather pointless here I'd say, it doesn't really do anything. 2) To motivate Zarko's use of thepositioninglibrary and its syntax, see http://tex.stackexchange.com/q/9386 3) And there are some newer alternatives to thetimespackage are better I believe (\usepackage{newtxtext,newtxmath}), see e.g. http://tex.stackexchange.com/questions/669 – Torbjørn T. Jan 18 '17 at 13:05