Transcendental Numbers – Does Schanuel’s Conjecture Imply ?^e is Transcendental?

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My understanding (and correct me if I'm wrong) is that it is unknown whether $\pi^e$ is algebraic or transcendental. I've also been led to believe that most open questions of this type would be solved by Schanuel's conjecture. For instance, the conjecture implies that $e$ and $\pi$ are algebraically independent, and in particular, $e+\pi$ and $e\pi$ are transcendental (currently it is unknown whether either is even rational).

Does Schanuel's conjecture also resolve whether $\pi^e$ is transcendental? (Note that the other way, $e^\pi$ – also called Gelfond's constant – is known to be transcendental by a special case of the Gelfond–Schneider theorem).

Best Answer

Yes, Schanuel's conjecture implies that $\pi^e$ is transcendental. First, note that it implies that $e$ and $\pi$ are algebraically independent: $1$ and $2\pi i$ are linearly independent over $\mathbb{Q}$, and so $\mathbb{Q}(1, 2\pi i, e, 1)$ has transcendence degree at least $2$ over $\mathbb{Q}$. It follows that $\log \pi$ cannot be rational, since that would give an algebraic dependence between $e$ and $\pi$. Therefore $1, 2\pi i, \log \pi$ are linearly independent over $\mathbb{Q}$, and so $\mathbb{Q}(1, 2\pi i, \log \pi, e, 1, \pi)$ has transcendence degree at least $3$ over $\mathbb{Q}$, which means $e$, $\pi$, and $\log \pi$ must be algebraically independent. This algebraic independence implies that $1, 2\pi i, \log \pi, e \log \pi$ are linearly independent over $\mathbb{Q}$, and thus $\mathbb{Q}(1, 2\pi i, \log \pi, e \log \pi, e, 1, \pi, \pi^e)$ has transcendence degree at least $4$ over $\mathbb{Q}$. Equivalently, $\mathbb{Q}(i, e, \pi, \log \pi, \pi^e)$ has transcendence degree at least $4$ over $\mathbb{Q}$, which means $e$, $\pi$, $\log \pi$, and $\pi^e$ must be algebraically independent.

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