A Proof from 'The Book'

By the way Huang assigned ‘-1’ for adjacency matrix, which puzzles me.

What is exciting is that he has a theorem says that:

Square root of the largest degree < the largest eigen value of an Adjacency matrix < largest degree. (see a picture below)

Huang used -1 in the adjacency matrix, not the Laplacian matrix. He assumes positive and negative interactions in his graphs

Question: normally, zero means no interaction?

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