# I Question about a definition in Rivasseau's book

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1. Apr 11, 2018

### Iliody

I have a problem understanding a definition at page 93 of 'from perturbative to constructive renormalization', that is related to Graph Theory, and he uses it on the proof of the uniform BPH theorem for $\phi_4^4$ ($\lambda \phi^4$ in $D=4$).
You have a graph G, a forest of quadrupeds F, and g a subgraph of G compatible with the tree structure of F. $B_F(g)$ is defined as the ancestor of g in FUG. What means ancestor in this context?
Maybe this question doesn't belong here, I'm sorry if that's the case. I thought that it belonged here because it's related to renormalization.

2. Apr 16, 2018

### PF_Help_Bot

Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.