Sasquatch

Sasquatch is a googologism based on an extension of the language of set theory. It was defined on the 27th March 2017 by user Emlightened. It is also called Big Bigeddon.

Definition of Sasquatch
We work in the language \((\in, \bar\in, &lt;)\), where equality is a defined symbol. \(\in\), \(\bar\in\) and \(&lt;\) are binary predicates, we also define the unary functions \(F\) and \(R\) from these. We then define the Sasquatch as the largest number \(k\) such that there is some unary formula \(\phi\) in the language \(\{\bar\in,Q\}\) (where \(Q(a,b) \leftrightarrow R(a)=b\)) of quantifier rank \(\leq 12\uparrow\uparrow 12\) such that \(\exists&#160;! a (\phi(a)) \wedge \phi(k)\).