Equation latex

[Duy Dinh]

\begin{equation}
    \label{formula:MaxMatcherSimilarity}
        I(w_i, t_j) = 
        \left\{         
            \begin{array}   {cc}
                \frac{1}{N(w_i) \times \sum_{w_{jk} \in t_j}{1/N(w_{jk})}} & \qquad \mathrm{if}\,$$w_i \in t_j$$\\
                0 & \qquad \mathrm{otherwise}
            \end{array} 
        \right\}
\end{equation}

[Duy Dinh]

\begin{equation}
\delta(Q_E, t) = \left\{
\begin{array}{ll}
1 & \mathrm{si}\, t \in Q_E \\
0 & sinon
\end{array}
\right.
\end{equation}