Let be the number of irredundant sets of size in a graph , then the irredundance polynomial of in the variable is defined as
It may also be written as
where is the upper irredundance number of (cf. Burger et al. 1997, Mynhardt and Roux 2020).
More things to try:
Weisstein, Eric W. "Irredundance Polynomial." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/IrredundancePolynomial.html
be the number of irredundant sets of size 
in a graph 
,
then the irredundance polynomial 
of 
in the variable 
is defined as
is the upper irredundance number of 
(cf. Burger et al. 1997, Mynhardt and Roux 2020).
