»ã±¨±êÌ⣨ÖÐÓ¢ÎÄ£© (Title)£º¸ßKazhdanͶӰºÍ·Ç²¿ÃÅ»¯l2±´µÙÊý£¨Higher Kazhdan projections and delocalised ?2-Betti numbers£©

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»ã±¨ÌáÒª£ºWe explicitly describe the K-theory class of higher Kazhdan projections for certain free product groups and Cartesian products. Employing the explicit description, we obtain new calculations of Lott¡¯s delocalised ?2-Betti numbers. In particular, we establish the first non-vanishing results for infinite groups.