Continuous Flattening of a Regular Tetrahedron with Explicit Mappings

We proved in [10] that each Platonic polyhedron $P$ can be folded into a flat multilayered face of $P$ by a continuous folding process of polyhedra. In this paper, we give explicit formulas of continuous functions for such a continuous flattening process in $\mathbb{R}^3$ for a regular tetrahedron.
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