Should tetration be a multivalued function?

[marraco]

Hold on we can do a bit better.

I need more clarification.

You propose \( \\[15pt]

{^0a\,^{^0a}=c_1\,^{c_2}=c_2\,^{c_1}=a\,^{c_1*c_2}} \), where the c's are the asymptotic values.

From sheldon we then get

a^(y z) = 16.

I do not understand from where comes that 16. y and z are defined by Sheldonison as functions of r.