In mathematics, a Perron number is an algebraic integer α which is real and greater than 1, but such that its conjugate elements are all less than α in absolute value.
For example, the larger of the two roots of the irreducible polynomial
Perron numbers are named after Oskar Perron; the Perron–Frobenius theorem asserts that, for a real square matrix with positive algebraic entries whose largest eigenvalue is greater than one, this eigenvalue is a Perron number.
As a closely related case, the Perron number of a graph is defined to be the spectral radius of its adjacency matrix.
You can help Wikipedia by expanding it.This graph theory-related article is a stub.