
\tikzstyle{group}=[rectangle, rounded corners, thick, draw=green,
  minimum size=5ex, inner sep=1.5ex]
\tikzstyle{action}=[rectangle, rounded corners, thick, draw=blue,
  minimum size=5ex, inner sep=1.5ex]
\tikzstyle{object}=[rectangle, sharp corners, thick, draw=purple,
  minimum size=5ex, inner sep=1.5ex]
\tikzstyle{robject}=[object, anchor=east]


\tikzstyle{arrseq}=[->, >=stealth, thick, draw=blue]
\tikzstyle{arrdat}=[->, >=stealth, thick, dashed, draw=red]
