On Schottky coverings of Drinfeld modular curves (Q1924923)

Drinfeld modular curves are Mumford curves at \(\infty\). We give explicit Schottky coverings for them. The most important fact is that, if \(M_\Gamma\) is the (affine) modular curve associated to the arithmetic group \(\Gamma\), then a Schottky group for \(\overline M_\Gamma\) (the canonical completion of \(M_\Gamma)\) appears to be a subgroup of \(\Gamma\), indeed its free part.