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Connes proved in his beautiful paper "Compact metric spaces, Fredholm modules, and hyperfiniteness" published in 1989 that if $(A,H,D)$ is a finitely summable spectral triple with a unital $C^*$-algebra $A$, then $A$ must have a tracial state. Here is the question: Is there an analogue of this result for non-unital spectral triples (for which $A$ is a non-unital $C^*$-algebra and $D$ has locally compact resolvents)? What are the main obstructions for existence of finitely summable spectral triples?

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According to MathSciNet, the paper you are referring to was published in 1989, not 1981: – Dmitri Pavlov Nov 21 '10 at 19:45
You are right! Thanks! – Kamran Reihani Feb 26 '11 at 21:14

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