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arXiv · 2608.23896

A counterexample to Haagerup's problem on subadditive weights

Ikhan Choi·Sunghyeon Jo
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Abstract

We construct a subadditive weight on the type I$_\infty$ factor that preserves directed suprema but is not $\sigma$-weakly lower semi-continuous. This provides a counterexample to Haagerup's first problem posed in 1975.

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Ikhan Choi, Sunghyeon Jo. 2026-08-24. A counterexample to Haagerup's problem on subadditive weights. https://arxiv.org/abs/2608.23896

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