PSD.4:4 - Solution
Set the problem boundary relative to one receiving use and one or more current formulations. Name what is included, material exclusions or unknowns, and the observable changes that can reopen the cut. Keep the reason for its adequacy where the recipient needs it to judge or use the scope. Use A.2.6 only when a receiving claim depends on exact U.ContextSlice membership in a declared U.Scope.
PSD.4:4.1 - Fix the receiving use and current formulations
Recover the subject, recipient, receiving decision or Work, horizon, and choice owner from the current PSD.1 engagement question or a qualified direct source for the same inquiry. Name the PSD.3 formulations whose consequences the boundary must preserve. Use one adequate current formulation directly when plural formulations are unnecessary. Keep a materially contested exclusion or boundary reason in the scope where it can change the receiving use.
Use a current PSD.2 account where participants, affected Systems, concerns, duties, interests, dissent, representation limits, or possible consequence paths can challenge the cut. Inclusion in that account does not require inclusion in every current model or analysis; exclusion from the boundary does require an honest reason when material. When an input needed for the cut is unavailable, stale, or incompatible, obtain a qualified direct result or return the exact missing premise. A formulation alone does not establish current representation or choice authority.
PSD.4:4.2 - State the boundary through decision-bearing dimensions
Name only dimensions that can change the receiving use:
- subject, configuration, place, population, and operating condition;
- included formulations and affected bearers;
- concerns, duties, interests, relations, dependencies, and consequence paths;
- evidence interval, uncertainty, and time horizon;
- intervention, adaptation, restraint, and no-action families; and
- participating, receiving, implementing, and choice-authority positions where material.
Carry forward the object distinctions recovered with the concerns. If “business trip” names both remote repair and administrative provision, say which work this inquiry concerns and which dependencies it includes. A boundary around expense processing cannot support a conclusion that the remote repair was completed. Several concerns about one identified journey can instead share that object boundary.
State the cut in ordinary language; add an exact U.Scope declaration only when the receiving use needs it. A boundary is not justified by drawing a box or using the word “system”.
PSD.4:4.3 - Keep material exclusions and unknowns alive
For every omitted item that could change a downstream result, record the item, exclusion reason, current evidence or uncertainty, consequence of being wrong, and reopen observation. Distinguish:
- outside for this receiving use from irrelevant in general;
- deferred from rejected;
- unknown membership from supported non-membership;
- absent evidence from evidence of absence; and
- a practical stopping decision from a claim that no relation or consequence exists.
Items with no plausible consequence for the current use need not receive a full record. Items that can reverse a high-consequence result require proportionate direct assurance or an explicit stop.
PSD.4:4.4 - Challenge the cut before accepting it
Apply the smallest relevant challenges:
- bearer challenge: could a participant or affected System outside the cut undergo a material change?
- formulation challenge: would another retained formulation include a different mechanism, value, horizon, or intervention family?
- action challenge: does the cut make one alternative appear necessary by excluding feasible restraint, adaptation, or no-action branches?
- evidence challenge: are data availability or model convenience defining the boundary?
- authority challenge: does the cut silently transfer a duty, jurisdiction, implementation burden, or later choice?
- reversal challenge: what smallest observation would make the current result unusable or materially different?
Repair only the affected dimension. A challenge does not require maximal widening.
PSD.4:4.5 - Use exact scope membership only when needed
When a downstream claim depends on whether one exact U.ContextSlice belongs to one declared U.Scope, use A.2.6. Distinguish an evaluation result of true, false, or unknown. Unknown means the available basis cannot decide; obtain the missing input, narrow the attempted use, or abstain instead of asserting exclusion. Changing the extension creates a new scope; a refit that preserves the extension does not.
Do not force every ordinary concern or participant into U.Scope. PSD.4 governs the field-specific judgement that a problem boundary is usable for the current inquiry; A.2.6 governs exact contextual membership. A C.2.3 formality threshold concerns how strictly a claim is expressed and is selected separately, only when the receiving use needs it.
PSD.4:4.6 - Return the usable scope and reopen basis
Return the scope in the smallest form that answers the current question. Keep the following content where it changes the recipient’s understanding or reliance; a local clarification can finish in the scope itself.
| Result position | Content needed by the recipient |
|---|---|
| receiving use | Subject, recipient, decision or Work, horizon, and retained choice owner. |
| formulation basis | Current formulations and the material differences the boundary preserves. |
| included scope | Bearers, concerns, relations, conditions, horizons, evidence, and intervention families included now. |
| exclusions and unknowns | Material omissions or uncertainties, reasons, consequences of error, and direct assurance still needed. |
| adequacy reason, where needed | Why this is the smallest usable scope, when the recipient needs that basis to judge the cut or avoid mistaking an exclusion for a settled fact. |
| dependent uses | Models, facilitation, alternatives, value treatment, comparison, recommendation, or inquiry results that consume the scope. |
| reopen basis | Observable triggers and the dimension to widen, narrow, replace, or re-formulate. |
If no defensible boundary is available, return the exact missing premise, blocker, narrowed claim, or abstention. Do not hide the stop by expanding the map.
PSD.4:4.7 - Reopen locally and state what changed
Reopen when a new participant, affected System, concern, formulation, relation, operating condition, evidence result, value tension, intervention family, horizon, receiving use, or authority fact can change the current result. Name the old boundary, new observation, affected dimension, and dependent result.
Widen, narrow, or replace only that portion. If a declared U.Scope or a relied-upon membership result changes, apply A.2.6; if the engagement identity or receiving use changes, return to PSD.1; if a new formulation is needed, return to PSD.3.
PSD.4:4.8 - What changes in practice
The practitioner stops treating scope as either the sponsor’s box or an ever-growing map. They can state a small usable cut, defend why exclusions are tolerable now, and show the precise observation that would reopen each consequential part.