The real rank versus completely positive rank conjecture for C*-algebras

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Let AA be a C∗C^*-algebra. Write rr A\mathrm{rr}\,A for its real rank and cpr A\mathrm{cpr}\,A for its completely positive rank.

Real-rank inequality conjecture. For every C∗C^*-algebra AA, one has

rr A≤cpr A.\mathrm{rr}\,A \leq \mathrm{cpr}\,A.

The inequality is motivated by examples in which real rank is at most completely positive rank, together with the expected agreement of completely positive rank with covering dimension for commutative algebras. Its resolution is not specified in the supplied text.

References

Primary source

Wilhelm Winter, “Covering Dimension for Nuclear C*-algebras”, arXiv:math/0107218 (2001).

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