{ \newcommand{\nodea}{\node[draw, diamond, aspect = 1] (a) {$t_1$}
;}\begin{tikzpicture}[auto]
\matrix[column sep=.3cm, row sep=.3cm,ampersand replacement=\&]{
 \nodea  \\
};
\end{tikzpicture}},{ \newcommand{\nodea}{\node[draw,diamond,aspect = 1,dashed] (a) {$...$}
;}\begin{tikzpicture}[auto]
\matrix[column sep=.3cm, row sep=.3cm,ampersand replacement=\&]{
 \nodea  \\
};
\end{tikzpicture}},{ \newcommand{\nodea}{\node[draw, diamond, aspect = 1] (a) {$t_k$}
;}\begin{tikzpicture}[auto]
\matrix[column sep=.3cm, row sep=.3cm,ampersand replacement=\&]{
 \nodea  \\
};
\end{tikzpicture}}