Multiexpansion refers to the function \(a \{\{2\}\} b = \{a,b,2,2\} = \underbrace{a \{\{1\}\} a \{\{1\}\} \ldots \{\{1\}\} a \{\{1\}\} a}_{ ext{b a's}}\), using BEAF. In the fast-growing hierarchy, \(f_{\omega+2}(n)\) is comparable to multiexpandal growth rate. That means two things: one is that Multiexpansion is comparable to Chained Arrow Notation and that Multiexpansion can be comparable in Notation Array by (a{3,3}b).