An effective estimate for the Lebesgue measure of preimages of iterates of the Farey map

Using techniques from infinite ergodic theory, Kesseböhmer and Stratmann determined the asymptotic behavior of the Lebesgue measure of sets of the form F−n[α,β]F−n[α,β], where [α,β]⊆(0,1][α,β]⊆(0,1] and F is the Farey map. In this paper, we provide an effective version of this result, employing mostly basic properties of the transfer operator of the Farey map and an application of Freud's effective version of Karamata's Tauberian theorem.