{"paper":{"title":"The 1-eigenspace for matrices in $\\operatorname{GL}_2(\\mathbb{Z}_\\ell)$","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"math.NT","authors_text":"Antonella Perucca, Davide Lombardo","submitted_at":"2016-12-08T21:27:54Z","abstract_excerpt":"Fix some prime number $\\ell$ and consider an open subgroup $G$ either of $\\operatorname{GL}_2(\\mathbb{Z}_\\ell)$ or of the normalizer of a Cartan subgroup of $\\operatorname{GL}_2(\\mathbb{Z}_\\ell)$. The elements of $G$ act on $(\\mathbb{Z}/\\ell^n \\mathbb{Z})^2$ for every $n\\geqslant 1$ and hence also on the direct limit, and we call 1-eigenspace the group of fixed points. We partition $G$ by considering the possible group structures for the 1-eigenspace and show how to evaluate with a finite procedure the Haar measure of all sets in the partition. The results apply to all elliptic curves defined "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1612.02845","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}