Four Fours/Lemmata/Three Fours/64/Solutions/2

Puzzle: Three Fours: $64$

Using exactly $3$ instances of the number $4$, the task is to write an expression for $64$, using whatever arithmetical operations you consider necessary.

Solution

$64 = 4 \uparrow \paren {\sqrt {\dfrac 4 {. \dot 4} } }$