I created a timeline with TikZ. The problem is, that there is a little gap between the ends of the braces that end at the same node.

And here is my code:
\begin{tikzpicture}[y=1cm, x=1cm, thick, font=\footnotesize]
% axis
\draw[line width=1.2pt, ->, >=latex'](0,0) -- coordinate (x axis) (10,0);
% time points
\draw (3,-4pt) node(t_k){} --
(3,4pt) node[anchor=south] {$t_{k}$};
\draw (5,-4pt) node(t_k_opt) {} --
(5,4pt) node[anchor=south] {};
\draw (7,-4pt) node(t_k_opt_impl) {} --
(7,4pt) node[anchor=south] {$t_{k}+\triangle^{\text{opt}}+\triangle^{\text{impl}}$};
% curly braces
\draw[decorate,decoration={brace,amplitude=3pt,mirror}]
(3,-2.5) node(t_k_unten){} --
(5,-2.5) node(t_k_opt_unten){};
\node at (4,-3){$\triangle^{\text{opt}}$};
\draw[decorate,decoration={brace,amplitude=3pt,mirror}]
(t_k_opt_unten) --
(7,-2.5) node(t_k_opt_impl_unten){};
\node at (6,-3){$\triangle^{\text{impl}}$};
% vertical dotted lines
\draw[dotted] (t_k)--(t_k_unten);
\draw[dotted] (t_k_opt)--(t_k_opt_unten);
\draw[dotted] (t_k_opt_impl)--(t_k_opt_impl_unten);
\end{tikzpicture}
I'd be glad, if someone could help!


coordinates instead ofnodes to mark coordinates on your path for later use (all starting witht_k). Usenodes=drawas a option to the TikZ picture to see what nodes do to the placement. – Qrrbrbirlbel Feb 12 '13 at 15:40