Christol–André conjecture on globally bounded D-finite power series

About 3 years old · traced to

Let y(x)=∑k≥0akxk∈Q[[x]]y(x)=\sum_{k\geq 0}a_kx^k\in\mathbb{Q}[[x]] be D-finite. Assume that the sequence (ak)k≥0(a_k)_{k\geq 0} has at most geometric growth, that there exists N∈NN\in\mathbb{N} such that y(Nx)−y(0)∈Z[[x]]y(Nx)-y(0)\in\mathbb{Z}[[x]], and that, in the minimal-order monic linear differential equation satisfied by y(x)y(x), x=0x=0 is not a pole of any coefficient ai(x)a_i(x). Christol–André conjecture. Then y(x)y(x) is algebraic. This conjecture proposes an arithmetic strengthening of Eisenstein's theorem: suitable integrality and growth conditions, together with a regularity condition at the origin, should force a D-finite series to be algebraic. The source presents it as open; it also mentions a variant replacing the third condition by the absence of logarithms in the local solutions at x=0x=0.

References

Primary source

Alin Bostan, Xavier Caruso and Julien Roques, “Algebraic solutions of linear differential equations: an arithmetic approach”, arXiv:2304.05061 (2024).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.