1.NounThe number of vertices in a maximum independent set of a given graph, often denoted as
α
=
α
(
G
)
{\displaystyle \alpha =\alpha (G)}
.
2.NounThe smallest cardinality of a maximal independent family of subsets of the natural numbers, usually denoted by lowercase Fraktur letter
i
{\displaystyle {\mathfrak {i}}}
.