Graph Theory versus Minimum Rank for Index Coding [PDF]
We obtain novel index coding schemes and show that they provably outperform all previously known graph theoretic bounds proposed so far. Further, we establish a rather strong negative result: all known graph theoretic bounds are within a logarithmic ...
Dimakis, Alexandros G.+2 more
core +9 more sources
On the K-theory of twisted higher-rank-graph C*-algebras [PDF]
We investigate the K-theory of twisted higher-rank-graph algebras by adapting parts of Elliott's computation of the K-theory of the rotation algebras.
Aidan Sims+24 more
core +13 more sources
C*-algebras of higher-rank graphs from groups acting on buildings, and explicit computation of their K-theory [PDF]
We unite elements of category theory, K-theory, and geometric group theory, by defining a class of groups called $k$-cube groups, which act freely and transitively on the product of $k$ trees, for arbitrary $k$. The quotient of this action on the product
Mutter, Sam A.+2 more
core +9 more sources
A dual graph construction for higher-rank graphs, and $K$-theory for finite 2-graphs [PDF]
Given a $k$-graph $\Lambda$ and an element $p$ of $\NN^k$, we define the dual $k$-graph, $p\Lambda$. We show that when $\Lambda$ is row-finite and has no sources, the $C^*$-algebras $C^*(\Lambda)$ and $C^*(p\Lambda)$ coincide.
Allen, Stephen, Pask, David, Sims, Aidan
core +10 more sources
Real and complex K-theory for higher rank graph algebras arising from cube complexes [PDF]
Using the Evans spectral sequence and its counter-part for real $K$-theory, we compute both the real and complex $K$-theory of several infinite families of $C^*$-algebras based on higher-rank graphs of rank $3$ and $4$. The higher-rank graphs we consider arise from double-covers of cube complexes. By considering the real and complex $K$-theory together,
Jeffrey L. Boersema, Alina Vdovina
semanticscholar +5 more sources
THE K-THEORY OF THE -ALGEBRAS OF 2-RANK GRAPHS ASSOCIATED TO COMPLETE BIPARTITE GRAPHS [PDF]
AbstractUsing a result of Vdovina, we may associate to each complete connected bipartite graph$\kappa $a two-dimensional square complex, which we call a tile complex, whose link at each vertex is$\kappa $. We regard the tile complex in two different ways, each having a different structure as a$2$-rank graph.
Sam A. Mutter
openalex +5 more sources
Structure theory and stable rank for C*-algebras of finite higher-rank graphs [PDF]
AbstractWe study the structure and compute the stable rank of$C^{*}$-algebras of finite higher-rank graphs. We completely determine the stable rank of the$C^{*}$-algebra when the$k$-graph either contains no cycle with an entrance or is cofinal. We also determine exactly which finite, locally convex$k$-graphs yield unital stably finite$C^{*}$-algebras ...
David Pask, Adam Sierakowski, Aidan Sims
openalex +5 more sources
K-theory and homotopies of 2-cocycles on higher-rank graphs [PDF]
This paper continues our investigation into the question of when a homotopy $ = \{ _t\}_{t \in [0,1]}$ of 2-cocycles on a locally compact Hausdorff groupoid $\mathcal{G}$ gives rise to an isomorphism of the $K$-theory groups of the twisted groupoid $C^*$-algebras: $K_*(C^*(\mathcal{G}, _0)) \cong K_*(C^*(\mathcal{G}, _1)).$ In particular, we ...
Elizabeth Gillaspy
openalex +5 more sources
The accuracy of anomaly detection in hyperspectral images (HSIs) faces great challenges due to the high dimensionality, redundancy of data, and correlation of spectral bands.
Shangzhen Song+3 more
doaj +2 more sources
Rank-two 5d SCFTs from M-theory at isolated toric singularities: a systematic study [PDF]
We carry out a detailed exploration of the deformations of rank-two five-dimensional superconformal field theories (SCFTs) T X $$ {\mathcal{T}}_{\mathbf{X}} $$ , which are geometrically engineered by M-theory on the space transverse to isolated toric ...
Vivek Saxena
doaj +2 more sources