Connes-Dixmier Traces, Singular Symmetric Functionals, and the Notion of Connes Measurable Element

This paper continues the study started in [1–5]. We show that the construction of abnormal traces used in [1, 2] can adequately be expressed by using the construction of singular symmetric functionals developed in [4, 5]. We completely describe the measurable elements on which all singular symmetric functionals from a certain class take the same values [1]. This result significantly complements the description of the structure of the set of measurable operators even in the special case studied in [1]. For natural subsets of the set of singular symmetric functionals, we obtain new results concerning their normalization properties.