In MALLET topic modelling, the --output-topic-keys [FILENAME] option outputs beside each topic a parameter that in the tutorial in the MALLET site called "Dirichlet parameter " of the topic.
I want to know what does this parameter represent? is it β in the LDA model? and if not what is it and what is it's meaning and use.
I noted that when I don't use the parameter optimization option while generating the topic model, this parameter differs in version 2.0.7 than in version 2.0.8. I want to know why this difference happens.
here's version 2.0.7 output
and 2.0.8
I know that the output differs by each run, but I am only concerned with this parameter.