Interesting. Quick question though:

    tau@eletron:~$ lax -c '((x-1) ** ((x-1)/(x+2)))/(y-z+k-e+w)'
    \frac{\sqrt[\left(\frac{x-1}{x+2}\right)]{\left(x-1\right)}}{y-z+k-e+w}

That does not make sense to me. Why do you use a root here? A root with that long of a degree just looks weird to me [1].

And even if, does the degree of the root not have to be inverted? I.e.:

    x**(y/z) == \sqrt[z/y]{x}

[1] http://latex.codecogs.com/gif.latex?%5Cfrac%7B%5Csqrt%5B%5Cl...