We use tools from combinatorial group theory in order to study actions of three types on groups acting on a curve, namely the automorphism group of a compact Riemann surface, the mapping class group acting on a surface (which now is allowed to have some points removed) and the absolute Galois group \(\mathrm{Gal}( \bar{\mathbb{Q}} /\mathbb{Q})\) in the case of cyclic covers of the projective line.
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