Complexity rank for C∗-algebras

Complexity rank for C∗-algebras
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发表时间:
2022
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通讯作者:
A. Jaime;R. Willett
A. Jaime;R. Willett
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其他
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作者:
A. Jaime;R. Willett

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C-代数的复杂性秩是由第二作者和Yu引入的,用于UCT的应用:非常粗略地说,如果你可以重复地将C-代数切成两半最多n次,并且最终得到有限维的东西,那么这个秩最多为n。在本文中,我们研究了复杂性秩,也是一个弱的复杂性秩,我们引入,有弱复杂性秩最多可以被认为是“双色局部有限维”。我们首先证明了对于可分的、有单位元的和单的C-代数,弱复杂度秩1等价于核维数1和真实的秩0的合取。特别地,这表明所有核C-代数的UCT等价于弱复杂性秩与具有零K-理论群的基希贝格代数的复杂性秩相等。然而,我们也表明,使用K理论的障碍(扭转K1),弱复杂性秩1和复杂性秩1是不一样的。然后,我们使用Kirchberg-Phillips分类定理来计算所有UCT基希贝格代数的复杂度秩:它总是1或2,秩1的情况发生当且仅当K1-群是无挠的。夏威夷大学马诺阿分校,2565麦卡锡购物中心,凯勒401 A,檀香山,HI 96816,美国; ajaime@hawaii.edu。夏威夷大学马诺阿分校,2565麦卡锡购物中心,凯勒401 A,檀香山,HI 96816,美国; rufus@math.hawaii.edu。1 ar X iv:2 20 5. 04 70 4v 2 [ m at h. O A ] 1 1 O ct 2 02 2
Complexity rank for C∗-algebras was introduced by the second author and Yu for applications towards the UCT: very roughly, this rank is at most n if you can repeatedly cut the C∗-algebra in half at most n times, and end up with something finite dimensional. In this paper, we study complexity rank, and also a weak complexity rank that we introduce; having weak complexity rank at most one can be thought of as ‘two-colored local finite-dimensionality’. We first show that for separable, unital, and simple C∗-algebras, weak complexity rank one is equivalent to the conjunction of nuclear dimension one and real rank zero. In particular, this shows that the UCT for all nuclear C∗-algebras is equivalent to equality of the weak complexity rank and the complexity ranks for Kirchberg algebras with zero K-theory groups. However, we also show using a K-theoretic obstruction (torsion in K1) that weak complexity rank one and complexity rank one are not the same in general. We then use the Kirchberg-Phillips classification theorem to compute the complexity rank of all UCT Kirchberg algebras: it is always one or two, with the rank one case occurring if and only if the K1-group is torsion free. University of Hawai‘i at Mānoa, 2565 McCarthy Mall, Keller 401A, Honolulu, HI 96816, USA; ajaime@hawaii.edu. University of Hawai‘i at Mānoa, 2565 McCarthy Mall, Keller 401A, Honolulu, HI 96816, USA; rufus@math.hawaii.edu. 1 ar X iv :2 20 5. 04 70 4v 2 [ m at h. O A ] 1 1 O ct 2 02 2