Rewrite `1 ** x` to `1`

[jessegrabowski]

Description

This is another useless operation rewrite in the flavor of 0 * x = 0. We could potentially also do 0 ** x = 0, but only if we were somehow positive (pun intended) that x is strictly positive.

[ricardoV94]

Out of curiosity did you have this in a real graph or just playing with trivial examples?

[jessegrabowski]

Yeah, in my phd model I have expressions that are very complex, but for fitting I'm interested in the case where some parameter is fixed to 1, which results in significant simplification. Something like:

$$ \frac{1 - \phi \beta \pi ^x}{1 - \phi \beta \pi ^y} $$

Where $x$ and $y$ are also big expressions. The whole thing dumps down to 1 if $\pi = 1$, but only if we can see the power simplification first.

[ricardoV94]

This is another useless operation rewrite in the flavor of 0 * x = 0. We could potentially also do 0 ** x = 0, but only if we were somehow positive (pun intended) that x is strictly positive.

We can add such rewrites, just not enabled by default. With some tag like "assume_defined_behavior" or "fast_math", or whatever