Christopher J. Eagle

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20242026

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math.OA2026

Non-computability of $K$ -theory for computably presented C*-algebras

Christopher J. Eagle, Isaac Goldbring, Timothy H. McNicholl +1

We give an example of a unital C*-algebra $A$ with a computable presentation and for which neither $K_{0} (A)$ nor $K_{1} (A)$ has a computable presentation.

math.LO2026

The computable functional calculus

Christopher J. Eagle, Timothy H. McNicholl

We show that the continuous functional calculus is computable. As consequences we obtain the computable compactness of the spectrum of any computable normal element of a computably…

math.OA2026

Computable $K$ -theory for C*-algebras II: AF algebras

Christopher J. Eagle, Isaac Goldbring, Timothy H. McNicholl

We continue the study of the effective content of $K$ -theory for C*-algebras, with a focus on AF algebras. We show that from a c.e. presentation of an AF algebra it is possible to…

Non-computability of K-theory for computably presented C*-algebras

The computable functional calculus

Computable K-theory for C*-algebras II: AF algebras

Non-computability of $K$ -theory for computably presented C*-algebras

Computable $K$ -theory for C*-algebras II: AF algebras