Low complexity among principal fully irreducible elements of Out(F3)
Naomi Andrew, Paige Hillen, Rylee Alanza Lyman, Catherine Pfaff · Algebraic & Geometric Topology · 2026
We find the shortest realized stretch factor for a fully irreducible ' 2 Out.F 3 / and show that it is realized by a "principal" fully irreducible element.We also show that it is the only principal fully irreducible outer automorphism in any rank produced by a single fold.