Then we say that the sequence $$ \begin{equation*} Q_N(f) = \sum_{i=1}^N\omega_i^{(N)}f(x_i^{(N)}), \end{equation*} $$ is convergent for all polynomials \( p \), that is $$ \begin{equation*} Q_N(p) = Q(p) \end{equation*} $$ if there exits a constant \( C \) such that $$ \begin{equation*} \sum_{i=1}^N|\omega_i^{(N)}| \le C, \end{equation*} $$ for all \( N \) which are natural numbers.