Understanding the Model Function for Generative model

With the reference to the paper on the generative models ---- "
https://arxiv.org/pdf/1705.10225.pdf "

It is supposed to be an introductory publication on the generative model
idea used in graph-tool but I am having little difficulty in understanding
the equation 4, the model generating function using Lagrange Multiplier.

A little more explanation of how this equation arrived, will be very much
helpful. A reference to further reading to understand this will also be very
helpful.

Hi,

Since this is not really a question about graph-tool, it is not suitable for
this list. If you wish to respond, please do so privately.

Furthermore, asking simply for "more explanation" is not helpful, since it
is difficult to guess what you have not understood. If you want to learn
about Lagrange multipliers, there are many available resources, e.g.

    https://en.wikipedia.org/wiki/Lagrange_multiplier

As for further references, the paper you cite has more than 100 of them...
What other kind of further reading do you want?

Best,