Generalizing quasi-ideals to the context of biacts

In 1978 a Hungarian mathematician, Otto Steinfeld, published a monograph of quasi-ideals over semigroups/rings, which can be defined as the intersection of a right- and left ideal. We will propose a generalization of the quasi-ideal, using the structure of a biact, and discuss the attempt of providing similar theory, as Steinfeld did for quasi-ideals. Furthermore, we will give some examples highlighting key differences between the quasi-ideal of a semigroup and a minor of a biact. There is insufficient time to go over all proofs given in the thesis, but we will, at the very least, mention some interesting similarities between (minimal) minors and Green's H-relation.