English

Patterns of Geodesics, Shearing, and Anosov Representations of the Modular Group

Geometric Topology 2026-05-13 v6

Abstract

Let X=SL3(R)/SO(3)X=SL_3(\R)/SO(3). Let DFR\cal DFR be the space of discrete faithful representations of the modular group into Isom\/(X){\rm Isom\/}(X) which map the order 22 generator to an isometry with a unique fixed point. I prove many things about the component B\cal B of DFR\cal DFR known as the Barbot component: It is homeomorphic to R2×[0,)\R^2 \times [0,\infty). The boundary parametrizes the Pappus representations from [{\bf S0\/}]. The interior parametrizes the complete extension of the family of Anosov representations from [{\bf BLV\/}]. The members of B\cal B are isometry groups of embedded patterns of geodesics in XX which have asymptotic properties like the edges of the Farey triangulation or shears thereof. The Anosov representations are obtained from the Pappus representations by either of two shearing operations in XX. The shearing structure is encoded by two proper foliations of B\cal B into rays.

Keywords

Cite

@article{arxiv.2412.18457,
  title  = {Patterns of Geodesics, Shearing, and Anosov Representations of the Modular Group},
  author = {Richard Evan Schwartz},
  journal= {arXiv preprint arXiv:2412.18457},
  year   = {2026}
}

Comments

This is a shorter version of the paper. In this version, I remove the material about morphed marked boxes and Anosov representations (Chapter 7 and some of Chapter 6). I made a new, self-contained material having that material. I made these changes to make all this work more modular and accessible. Otherwise the paper is the same