graceful-extensibility.md

Theorems of graceful extensibility

Source: The theory of graceful extensibility: basic rules that govern adaptive systems

Managing risk of saturation

Adaptive capacity is finite / boundaries are universal

The location of boundaries to the ability to meet demands is uncertain.

Given a finite range, there is a general parameter - capacity for maneuver (CfM) which specifies how much of the range the unit has used and what capacity reamints to handle upcoming demands.

Events will produce demands that challenge boundaries on the adaptive capacity of any UAB / Surprise occurs, continuously

There are recurring patterns that characterize model surprise - how events challenge boundaries:

• Events will occur at some rate and of some size and of some kind that increase the risk of saturation - exhausting the remaining CfM
• Brittleness is how rapidly a unit's eprformance declines when it nears and reaches its boundaries.
• The range of adaptive behavior of a UAB is a model of fitness.
• Events that occur near or outside a UAB's boundary increases the risk of stauration, and this occurs independent ofhow well that UAB matches responses to demands.

Adaptive capacities are regulated to manage the risk of saturating CfM / Risk of saturation is monitored and regulated

• The work required to adapt and handle changing demands increases as CfM decreases.
• As risk of saturation increases and CfM approaches exhaustion, UABs need to adapt to stretch or extend their base range of adaptive behavior to accomodate surprises.

Network of adaptive units

No UAB can have sufficient ability to regulate CfM to manage the risk of saturation alone / Synchronization across multiple units of adaptive behavior in a network is necessary

UABs exist in and are defined relative to a network of interacting and interdependent UABs at multiple scales → networks with multiple roles, multiple echelons

Some UABs monitor and regulate the CfM of other UABs in response to changes in the risk of saturation / Risk of saturation can be shared

Misalignment and mis-coordination across UABs increaes the risk of saturating control as demands grow and cascade.

Adaptive capacity is the potential for adjusting patterns of action to handle future situations, events, opportunities and disruptions / Pressure changes what is sacrificed when

What architectural properties of the network influence the way units in a network respond to varying pressures on trade-offs?

Outmaneuvering constraints

Performance of a UAB as it approaches saturation is different from the performance of that UAB when it operates far from saturation / Pressure for optimality undermines graceful extensibility

All UABs are local / All adaptive units are local

There are bounds on the perspective any UAB, but these limits are overcome by shifts and contrasts over multiple perspectives / Perspective contrast overcomes bounds

Reflective systems risk mis-calibration / Mis-calibration is the norm