Tensions in Practice: Local informed authority in tension with a centralized decision record¶
A job assignment with one stable readiness bit
A station knows whether it is ready to receive a job. The center initially sees the same job request in both ready and not-ready states, so that request alone cannot justify the rule “assign only if ready.” One arrangement delegates the final choice to the informed station. The other keeps the final choice at the center and sends it the readiness bit first. Both can apply the same rule; they place authority and communication costs differently.
Decide where the criterion is already known
Let the station own the final readiness decision.
Keep final authority at the center
Move the distinguishing readiness information before deciding.
Why these aims pull against each other
Correct ownership requires access to the information that distinguishes outcomes. Keeping authority centralized does not remove that requirement; it moves the burden into a communication path.
Choose an arrangement to see what changes and what remains difficult.
Station is on the left; center is on the right. The highlighted node owns the final decision and applies “assign if and only if ready.” The readiness bit stays local under delegation, or crosses to the central decision. It is stable for the declared decision epoch.
What this choice protects
What it costs
When it fits
Compare the arrangements
Move final authority to the station
Give the station the rule and authority to accept exactly when ready. The center does not approve each individual readiness choice.
- What it protects
- The final readiness choice uses information already present, without waiting for a central query–reply exchange.
- What it costs
- Authority and rule maintenance are distributed; the center does not produce an immediate inline record of every final decision.
- When it fits
- Fits a task in which delegating this bounded criterion is acceptable.
Illustration note: This delegates only the readiness decision, not every scheduling or resource policy. Later reporting may still be required and is outside the displayed immediate path.
Send the bit to the center
Retain final assignment authority centrally. Query the station, receive the current readiness bit, then apply the identical rule.
- What it protects
- Final decisions and their input bit can be recorded at one decision location.
- What it costs
- Each decision requires the bit to be communicated before action; the exchange adds a dependency and response time.
- When it fits
- Fits a task that values centralized final authority and can afford the information exchange.
Illustration note: Readiness is stipulated stable for the decision epoch, with reliable delivery. Without that condition, freshness and time-of-check issues would require an additional design.
What this illustration does—and does not—establish
The source supplies the structural tension. This bounded example makes a particular relation inspectable; the aims, conditions and residual costs are part of the comparison.
- Ready and not-ready are the only relevant states for this bounded criterion. The center initially receives identical requests in both.
- The example freezes the bit during the decision epoch; it does not claim communication generally guarantees current information.
- No measured latency or universal claim that local decisions are faster is made. The comparison names the extra communication dependency in this arrangement.
Source entries
Information Locality
The canonical tension motivates this comparison. The setting and arrangements are declared editorial illustrations, not observed findings.
Informed ownership versus response time
The best-informed level may be slower or farther from the event.
The source operation
Information Locality is the placement principle that responsibility for a decision, guarantee, or interpretation belongs at a level that possesses the information required to discharge it. A less-informed level may filter, accelerate, recommend, precheck, or catch some failures. It cannot own correctness when two states that require different outcomes remain indistinguishable from its position. The decisive relation is therefore not physical distance but *criterion–information fit*.