 The third challenge consists in describing the different ways in which processes relate to each other and especially, how they combine. Since process combinations may engender emergent processes, and also in other regards do not abide by the laws of Boolean algebra, neither set theory not classical extensional mereology can be used as formal frameworks ontologically to describe and classify different types of process combinations. Moreover, since the parthood relation on processes is not transitive, at least when processes are not identified with extended spatiotemporal regions, further deviations from the classical axiomatization of the parthood relations are necessary to formalize a mereology on  processes.[25]  Alternatively, some authors suggest representing process architectures with the means of mathematical category theory. Since some category-theoretically defined notions of compositionality restrict decomposition, proponents of “applied category theory” argue that interdependencies of (the identity of) wholes and parts in process structures also can be represented within this formalism without incurring substance-ontological commitments. Some authors recommend category theory for a formal Whiteheadian approach to process metaphysics (Ferrari 2021, Auxier &amp; Herstein 2017), while others use it to formulate notions of compositionality that can be applied across domains from computer science to quantum physics (Coecke 2017). Also systematic connections between process structures can be captured category-theoretically, as Phillips and Wilson (2010 ) show the case of the systematicity of cognitive capacities. Besides mereology and category theory, some authors explore formal dialectical theories in order to describe the “logic” of real changes (Brenner and Igamberdiev 2021).