The code for Mikolov et al. (2013b) and <cite>Xing et al. (2015)</cite> is not publicly available, so we implemented and tested them as part of the proposed framework, which only differs from the original systems in the optimization method (exact solution instead of gradient descent) and the length normalization approach in the case of <cite>Xing et al. (2015)</cite> (postprocessing instead of constrained training).