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arXiv · 2604.06982

Selfless reduced amalgamated free products and HNN extensions

David Gao·Srivatsav Kunnawalkam Elayavalli·Gregory Patchell·Lizzy Teryoshin
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Abstract

We find a general family of selfless inclusions in reduced amalgamated free products of C*-algebras. Apart from generalizing prior works due to McClanahan, Ivanov and Omland, our work yields a few other applications. We present a short new approach to construct HNN extensions of C*-algebras and find several new examples of selflessness using this. This generalizes results of Ueda, Ivanov and de la Harpe-Preaux. As another application our work yields a short proof of selflessness for arbitrary graph products of C*-algebras over graphs of more than 2 vertices and diameter greater than 3.

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David Gao, Srivatsav Kunnawalkam Elayavalli, Gregory Patchell, Lizzy Teryoshin. 2026-04-08. Selfless reduced amalgamated free products and HNN extensions. https://arxiv.org/abs/2604.06982

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