Browsing Institutt for matematiske fag by Author "Quigg, John"
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Coaction functors
Kaliszewski, Steve; Landstad, Magnus B.; Quigg, John (Journal article; Peer reviewed, 2016)A certain type of functor on a category of coactions of a locally compact group on C ∗ C∗-algebras is introduced and studied. These functors are intended to help in the study of the crossed-product functors that have ... -
Coaction functors, II
Kaliszewski, S; Landstad, Magnus Brostrup; Quigg, John (Journal article; Peer reviewed, 2018)In their study of the application of crossed-product functors to the Baum–Connes conjecture, Buss, Echterhoff, and Willett introduced various properties that crossed-product functors may have. Here we introduce and study ... -
Exact large ideals of B(G) are downward directed.
Kaliszewski, Steve; Landstad, Magnus B.; Quigg, John (Journal article; Peer reviewed, 2016)We prove that if E and F are large ideals of B(G) for which the associated coaction functors are exact, then the same is true for E∩F. We also give an example of a coaction functor whose restriction to the maximal coactions ... -
Exotic Coactions
Landstad, Magnus B.; Kaliszewski, Steve; Quigg, John (Journal article; Peer reviewed, 2016)If a locally compact group G acts on a C *-algebra B, we have both full and reduced crossed products and each has a coaction of G. We investigate ‘exotic’ coactions in between the two, which are determined by certain ideals ... -
Ordered invariant ideals of Fourier-Stieltjes algebras
Landstad, Magnus Brostrup; Kaliszewski, Steve; Quigg, John (Journal article; Peer reviewed, 2018)For a locally compact group G, every G-invariant subspace E of the Fourier-Stieltjes algebra B(G) gives rise to the following two ideals of the group C ∗ -algebra C ∗ (G): the intersection of the kernels of the representations ... -
Properness conditions for actions and coactions
Landstad, Magnus B.; Kaliszewski, Steve; Quigg, John (Journal article; Peer reviewed, 2016)Three properness conditions for actions of locally compact groups on C⇤-algebras are studied, as well as their dual analogues for coactions. To motivate the properness conditions for actions, the commutative cases (actions ... -
Tensor-product coaction functors
Kaliszewski, Steve; Landstad, Magnus Brostrup; Quigg, John (Peer reviewed; Journal article, 2020)Recent work by Baum et al. [‘Expanders, exact crossed products, and the Baum–Connes conjecture’, Ann. K-Theory 1(2) (2016), 155–208], further developed by Buss et al. [‘Exotic crossed products and the Baum–Connes conjecture’, ...