Brownawell–Yu conjecture on algebraic independence of Drinfeld logarithms

Let ρ\rho be a Drinfeld Fq[t]\mathbb{F}_q[t]-module defined over k\overline{k}. Suppose Fδ1,,FδsF_{\delta_1},\dots,F_{\delta_s} are quasi-periodic functions for C\mathbb{C}_\infty-linearly independent biderivations δ1,,δs\delta_1,\dots,\delta_s in D(ρ)/Di(ρ)D(\rho)/D_i(\rho), defined over k\overline{k}. Let λ1,,λmC\lambda_1,\dots,\lambda_m\in\mathbb{C}_\infty satisfy expρ(λi)k\exp_\rho(\lambda_i)\in\overline{k} for i=1,,mi=1,\dots,m, and suppose that λ1,,λm\lambda_1,\dots,\lambda_m are linearly independent over KρK_\rho. Brownawell–Yu conjecture. The m(s+1)m(s+1) quantities

λ1,,λm,j=1s{Fδj(λ1),,Fδj(λm)}\lambda_1,\dots,\lambda_m,\quad \bigcup_{j=1}^s\{F_{\delta_j}(\lambda_1),\dots,F_{\delta_j}(\lambda_m)\}

are algebraically independent over k\overline{k}. This conjecture predicts that, for Drinfeld logarithms of algebraic functions, the linear relations over the multiplication ring of the Drinfeld module are the only algebraic relations. It strengthens the known linear-independence theorem of Brownawell and Yu, while its general status is unresolved.

Sources & referencesView supporting material

Primary source

Chieh-Yu Chang and Matthew A. Papanikolas, “Algebraic relations among periods and logarithms of rank 2 Drinfeld modules”, arXiv:0807.3157 (2008).

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