UNITAL EMBEDDINGS OF C*-ALGEBRAS THAT ONE CAN SEE

Speaker(s)

YANG LIU

Affiliation

SISSA, Trieste, Italy

Language of the talk

English

Date

March 25, 2026, 5:15 p.m.

Information about the event

IMPAN - Room 405 & zoom

Title in Polish

UNITAL EMBEDDINGS OF C*-ALGEBRAS THAT ONE CAN SEE

Seminar

North Atlantic Noncommutative Geometry Seminar

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Cuntz algebras On, n>1, are celebrated examples of a separable infinite simple C*-algebra with a number of fascinating properties. Their K-theory allows an embedding of Om in On whenever n−1 divides m−1. In 2009, Kawamura provided a simple and explicit formula for all such embeddings. It turns out that his formulas can be easily deduced by viewing Cuntz algebras as graph C*-algebras, known as operator algebras that one can see. Better still, playing the game of graphs and using both the covariant and contravariant functoriality of assigning graph C*-algebras to directed graphs, we can show how to embed Cuntz algebras into matrices over Cuntz algebras via straightforward polynomial formulas. Based on joint work with Piotr M. Hajac.

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