Within a supply chain, some (sub)activity systems are sequential, while others are parallel.  An example of sequential (sub)activity systems is mixing  the dough before baking it. An example of parallel (sub)activity systems is preheating the oven while mixing the dough.

The parallel (sub)activity systems at one level in the systems hierarchy can become sequential at another level. For example, society’s education activity system consists of the parallel sub-activity systems of primary, secondary and tertiary education. At the individual level, these become sequential. The learners have to complete primary, then secondary education before entering tertiary education. Likewise, in a cake factory the assembling, mixing and baking phases exist parallel (i.e. they exist as so-called line functions), even if each cake has to go through these phases sequentially.

relevance

Even if activity systems, like all systems, are a space-time continuum, parallel (sub)activity systems highlight the spatial perspective, while sequential (sub)activity systems emphasise the temporal perspective.

relevance for the change manager

Activity system (re)design (e.g. business process or functional redesign) involves both sequential and parallel (sub)activity systems.

what is the relevance of this concept for you?