Partially Positive Semidefinite Maps on $*$-Semigroupoids and Linearisations (2302.13107v2)

Abstract: Motivated by Cuntz-Krieger-Toeplitz systems associated to undirected graphs and representations of groupoids, we obtain a generalisation of the Sz-Nagy's Dilation Theorem for operator valued partially positive semidefinite maps on $$-semigroupoids with unit, with varying degrees of aggregation, firstly by $$-representations with unbounded operators and then we characterise the existence of the corresponding $$-representations by bounded operators. By linearisation of these constructions, we obtain similar results for operator valued partially positive semidefinite maps on $$-algebroids with unit and then, for the special case of $B^*$-algebroids with unit, we obtain a generalisation of the Stinespring's Dilation Theorem. As an application of the generalisation of the Stinespring's Dilation Theorem, we show that some natural questions on $C^*$-algebroids are equivalent.