Efficient presentations of relative Cuntz-Krieger algebras (Q2036590)

The authors first give the definition of higher-rank graphs and establish notation. They introduce efficient sets and give examples. They show that for a directed graph \(E\), every set of regular vertices of \(E\) can be viewed as an efficient set. They introduce \(\varepsilon\)-boundary paths. They use these paths to establish properties of the universal relative Cuntz-Krieger algebras. Finally, they discuss applications.