Ranks of matrices of logarithms of algebraic numbers I: the theorems of Baker and Waldschmidt-Masser

Abstract

Let $\mathcal{L}$ denote the $\mathbf{Q}$-vector space of logarithms of algebraic numbers. In this expository work, we provide an introduction to the study of ranks of matrices with coefficients in $\mathcal{L}$. We begin by considering a slightly different question, namely we present a proof of a weak form of Baker's Theorem. This states that a collection of elements of $\mathcal{L}$ that is linearly independent over $\mathbf{Q}$ is in fact linear independent over $\overline{\mathbf{Q}}$. Next we recall Schanuel's Conjecture and prove Ax's analogue of it over $\mathbf{C}((t))$. We then consider arbitrary matrices with coefficients in $\mathcal{L}$ and state the Structural Rank Conjecture, which gives a conjecture for the rank of a general matrix with coefficients in $\mathcal{L}$. We prove the theorem of Waldschmidt and Masser, which provides a lower bound giving a partial result toward the Structural Rank Conjecture. We conclude by stating a new conjecture that we call the Matrix Coefficient Conjecture, which gives a necessary condition for a square matrix with coefficients in $\mathcal{L}$ to be singular.

45 pages