In our implementation, this statement is equivalent with the process of randomly selecting for the first event mention a number of Poisson(α ′ ) observed feature values.
in the general case, the sampling of the binary variable from the m th Markov chain and associated with the t th event mention depends on the value assigned to the hidden variable in the previous t − 1 step: in our implementation, the observed feature value f m is selected for the t th event mention according to the probabilities presented in Equation (11).