Spectral gap of scl in free products

Chen, Lvzhou

doi:10.1090/proc/13899

Spectral gap of scl in free products
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Proc. Amer. Math. Soc. 146 (2018), 3143-3151 Request permission

Abstract:

Let $G=*_\lambda G_\lambda$ be a free product of torsion-free groups, and let $g\in [G,G]$ be any element not conjugate into a $G_\lambda$. Then $\mathrm {scl}_G(g)\ge 1/2$. This generalizes and gives a new proof of a theorem of Duncan and Howie (1991).

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