Abstract
It is well known that any W-operator can be represented as the supremum (respectively, infimum) of sup-generating and (respectively, inf-generating) operators, that is, the families of sup-generating and inf-generating operators constitute the building blocks for representing W-operators. Here, we present two new families of building blocks to represent W-operators: compositions of sup-generating operators with dilations and compositions of inf-generating operators with erosions. The representations based on these new families of operators are called, respectively, sup-compact and inf-compact representations, since they may use less building blocks than the classical sup-generating and inf-generating representations. Considering the W-operators that are both anti-extensive and idempotent –in a strict sense–, we have also gotten a simplification of the sup-compact representation. We have also shown how the inf-compact representation can be simplified for any W-operator such that it is extensive and its dual operator is idempotent –in a strict sense–. Furthermore, if the W-operators are openings (respectively, closings), we have shown that this simplified sup-compact (respectively, inf-compact) representation reduces to a minimal realization of the classical Matheron's representations for translation invariant openings (respectively, closings).