KFD-2 formal reference

KFD-2 Formal Reference

Authoritative decision · Formal model · Usage · Documentation map

• Status: experimental
• Normative: no
• Formal model version: 1
• Authority: decisions/KFD-2.md
• Decision status: active

Imported vocabulary

Claim, FactBinding, Evidence, AuditBoundary, AssuranceResponsibility, ResidualRisk, TrustAssessment.

Domain objects

For a claim c, define:

Subject(c)          exact object of reliance
Statement(c)        bounded proposition
Facts(c)            inspectable fact bindings
Evidence(c)         checked support or contradiction
Boundary(c)         declared audit scope and enumerability
Responsibility(c)   source, verification, and decision owners
Risk(c)             known residual risk

The assessment function is:

Assess(c, Facts, Evidence, Boundary, Responsibility, Risk)
  -> pass | warning | fail | unverifiable

Relations and predicates

Bound(c, f)          claim c identifies fact f
Checked(e)           evidence e was actually evaluated
Within(e, b)         evidence e is inside audit boundary b
Owned(r)             responsibility role r has a named owner
Contradicts(e, c)    checked evidence conflicts with c
Exceeds(c, b)        the claimed reliance exceeds the audited boundary

Invariants

I1  Assessed(c) -> Exact(Subject(c)) and Exact(Statement(c))
I2  Result(c) in {pass, warning} -> Facts(c) is not empty
I3  Checked(e) -> Within(e, Boundary(c))
I4  Assessed(c) -> Owned(source) and Owned(verification) and Owned(decision)
I5  Risk(c) is not empty -> Risk(c) is exposed in the assessment
I6  Contradicts(e, c) -> Reassess(c)
I7  Exceeds(c, Boundary(c)) -> Result(c) != pass

Trust is bounded and revisable. It is not monotonic: additional evidence may increase, reduce, redirect, or remove justified reliance.

Assessment transition

declared claim
  -> facts bound
  -> evidence checked
  -> boundary and responsibility fixed
  -> residual risk classified
  -> assessment issued
  -> reassessed when contradictory or boundary-changing evidence appears

Proof obligations

• State the exact subject and proposition.
• Bind the proposition to non-drifting fact sources where available.
• Distinguish checked evidence from merely referenced material.
• Declare what was not checked.
• Name source, verification, and decision responsibility.
• Expose residual risk and downgrade reason.
• Keep the assessment exportable and reviewable.

Invalid states

• A pass result with no fact binding.
• Evidence outside the declared boundary presented as checked.
• Reputation, authority, calibration, or persuasive explanation substituted for facts.
• Residual risk hidden from the participant relying on the claim.
• Contradictory evidence ignored because the original assessor is trusted.

Machine mappings

Non-claims and extension points

KFD-2 does not guarantee truth, complete capture, or exhaustive machine proof. It specifies when reliance is inspectable and who remains responsible. Domain-specific claim kinds and assessment procedures may be added if they preserve bounded evidence, explicit residual risk, and revisability.