Abstract
For a given finite index subgroup \(H\subseteq \mathrm {SL}(2,\mathbb {Z})\), we use a process developed by Fisher and Schmidt to lift a Poincaré section of the horocycle flow on \(\mathrm {SL}(2,\mathbb {R})/\mathrm {SL}(2,\mathbb {Z})\) found by Athreya and Cheung to the finite cover \(\mathrm {SL}(2,\mathbb {R})/H\) of \(\mathrm {SL}(2,\mathbb {R})/\mathrm {SL}(2,\mathbb {Z})\). We then use the properties of this section to prove the existence of the limiting gap distribution of various subsets of Farey fractions. Additionally, to each of these subsets of fractions, we extend solutions by Xiong and Zaharescu, and independently Boca, to a Diophantine approximation problem of Erdős, Szüsz, and Turán.
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References
Athreya, J.S.: Gap distributions and homogeneous dynamics. Preprint arXiv:1210.0816 math.DS, to appear. In: Proceedings of ICM Satellite Conference on Geometry, Topology, and Dynamics in Negative Curvature
Athreya, J.S., Chaika, J., Leliévre, S.: The gap distribution of slopes on the golden L. Contemp. Math. 631, 47–62 (2015)
Athreya, J.S., Cheung, Y.: A Poincaré section for the horocycle flow on the space of lattices. Int. Math. Res. Notices 10, 2643–2690 (2014)
Athreya, J.S., Ghosh, A.: The Erdős-Szüsz-Turán distribution for equivariant processes. Preprint arXiv:1508.01886 math.DS
Augustin, V., Boca, F.P., Cobeli, C., Zaharescu, A.: The \(h\)-spacing distribution between Farey points. Math. Proc. Camb. 131(1), 23–38 (2001)
Badziahin, D.A., Haynes, A.K.: A note on Farey fractions with denominators in arithmetic progressions. Acta Arith. 147(3), 205–215 (2011)
Billingsley, P.: Convergence of Probability Measures. Wiley, New York (1968)
Boca, F.P.: A problem of Erdős, Szüsz, and Turán concerning diophantine approximations. Int. J. Numb. Theory 4(4), 691–708 (2008)
Boca, F.P., Cobeli, C., Zaharescu, A.: A conjecture of R. R. Hall on Farey points. J. Reine Angew. Math. 535, 207–236 (2001)
Boca, F.P., Gologan, R.N., Zaharescu, A.: The average length of a trajectory in a certain billiard in a flat two-torus. New York J. Math. 9, 303–330 (2003)
Boca, F.P., Heersink, B., Spiegelhalter, P.: Gap distribution of Farey fractions under some divisibility constraints. Integers 13, A#44 (2013)
Boca, F.P., Zaharescu, A.: The correlations of Farey fractions. J. Lond. Math. Soc. 72(1), 25–39 (2005)
Elkies, N., McMullen, C.: Gaps in \(\sqrt{n} \,\text{ mod }\, 1\) and ergodic theory. Duke Math. J. 123(1), 95–139 (2004)
Erdős, P., Szüsz, P., Turán, P.: Remarks on the theory of Diophantine approximation. Colloq. Math. 6, 119–126 (1958)
Eskin, A., McMullen, C.: Mixing, counting, and equidistribution in Lie groups. Duke Math. J. 71(1), 181–209 (1993)
Fisher, A.M., Schmidt, T.A.: Distribution of approximants and geodesic flows. Ergod. Theor. Dyn. Sys. 34(6), 1832–1848 (2014)
Hall, R.R.: A note on Farey series. J. Lond. Math. Soc. 2, 139–148 (1970)
Hedlund, G.: Fuchsian groups and transitive horocycles. Duke Math. J. 2(3), 530–542 (1936)
Hejhal, D.A.: On the uniform equidistribution of long closed horocycles. In: Loo-Keng Hua: A Great Mathematician of the Twentieth Century, Asian J. Math. 4, 839–853. Int. Press, Somerville, MA (2000)
Howe, R., Moore, C.C.: Asymptotic properties of unitary representations. J. Funct. Anal. 32(1), 72–96 (1979)
Kargaev, P.P., Zhigljavsky, A.A.: Asymptotic distribution of the distance function to the Farey points. J. Numb. Theory 65, 130–149 (1997)
Kesten, H., Sós, V.T.: On two problems of Erdős, Szüsz and Turán concerning diophantine approximations. Acta Arith. 12, 183–192 (1966)
Marklof, J.: The asymptotic distribution of Frobenius numbers. Invent. Math. 181(1), 179–207 (2010)
Marklof, J.: Fine-scale statistics for the multidimensional Farey sequence. In: Eichelsbacher, P., Elsner, G., Kösters, H., Löwe, M., Merkl, F., Rolles, S. (eds.) Limit Theorems in Probability, Statistics and Number Theory: In Honour of Friedrich Götze, pp. 49–57. Springer, Heidelberg (2013)
Marklof, J., Strömbergsson, A.: The distribution of free path lengths in the periodic Lorentz gas and related lattice point problems. Ann. Math. 172(3), 1949–2033 (2010)
Sarnak, P.: Asymptotic behavior of periodic orbits of the horocycle flow and Eisenstein series. Commun. Pure Appl. Math. 34(6), 719–739 (1981)
Strömbergsson, A.: On the uniform equidistribution of long closed horocycles. Duke Math. J. 123(3), 507–547 (2004)
Xiong, M., Zaharescu, A.: Correlation of fractions with divisibility constraints. Math. Nachr. 284, 393–407 (2011)
Xiong, M., Zaharescu, A.: A problem of Erdős-Szüsz-Turán on diophantine approximation. Acta Arith. 125(2), 163–177 (2006)
Zagier, D.: Eisenstein series and the Riemann zeta function. In: Ramanathan, K.G. (ed.) Automorphic Forms, Representation Theory and Arithmetic (Bombay 1979), pp. 275–301. Tat Inst. Fund. Res, Bombay (1981)
Acknowledgments
I thank my advisor Florin Boca for his guidance in this research. I thank Jayadev Athreya and Jens Marklof for constructive comments on the first draft of this paper, and I thank the referee for helpful comments and suggestions.
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Communicated by S. G. Dani.
The author acknowledges support from Department of Education Grant P200A090062, “University of Illinois GAANN Mathematics Fellowship Project”.
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Heersink, B. Poincaré sections for the horocycle flow in covers of \(\mathrm {SL}(2,\mathbb {R})/\mathrm {SL}(2,\mathbb {Z})\) and applications to Farey fraction statistics. Monatsh Math 179, 389–420 (2016). https://doi.org/10.1007/s00605-015-0873-x
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DOI: https://doi.org/10.1007/s00605-015-0873-x