Experts in resilience engineering have been studying complex systems in high-stakes industries for decades. The Theory of Graceful Extensibility is organized around ten statements which describe properties found in complex systems from medicine, military, transportation, aviation, aerospace, power generation and transmission, and similar industries. The software business has finally caught up with those other industries in terms of complexity, and at the same time has become an essential part of all of those other systems.
The ten statements are organized into three groups. Inside each group there are relationships between the statements that complement, contrast, and compound each other. Between the three groups there are similar relationships of complement, contrast, and compounding. The diagram below over-simplifies these relationships. Like the systems these statements describe, things are much more entangled and woven together than any single model can capture. All models are wrong. We hope this model of the statements and groupings may be useful.
strict digraph { compound=true node [shape=box] subgraph cluster_MRoS { label="Managing Risk of Saturation" { S2 S1 } -> S3 } subgraph cluster_NoAU { label="Networks of Adaptive Units" { S5 S4 } -> S6 } subgraph cluster_OC { label="Outmaneuvering Constraints" { S9 S8 S7 } -> S10 } S3 -> S8 [ ltail=cluster_MRoS lhead=cluster_OC minlen=2 ] S6 -> S8 [ ltail=cluster_NoAU lhead=cluster_OC minlen=2 ] }
The opposite of brittleness in complex systems. David Woods presents a theory of graceful extensibility. This paper is dense and will reward further study. Know that it is not for the faint of heart.
Subset A: Managing Risk of Saturation. Teams must maintain or extend their Capacity for Maneuver as demands of finite resources and continuous change push them past current boundaries.
Subset B: Networks of Adaptive Units. Units affect each other's capacity to maneuver.
Subset C: Outmaneuvering Constraints. Observing capacity for maneuver and its risk of saturation among and between the tangled layers of units, the system can outmaneuver finite resources and continuous change.