Trust Graph
The trust graph is the persistent structure connecting subjects, producers, contexts, signals, and relationships in PTI.
Graph model
Node types
| Node | Key attributes |
|---|---|
| Subject | pti_id, identity_type, verification_level |
| Producer | producer_id, entitled contexts |
| Consumer | consumer_id, lookup tiers |
| Context | context_id, context_tier |
| Signal | signal_id, polarity, weight, effective_at |
| Evidence | evidence_id, evidence_type, hash |
Edge types
| Edge | Semantics |
|---|---|
EMITTED | Producer → Signal |
AFFECTS | Signal → Subject |
SCOPED_TO | Signal → Context |
SUPPORTED_BY | Signal → Evidence |
ENDORSES | Subject → Subject |
EMPLOYS | Organization → Individual |
VERIFIED_BY | Assertion → Producer |
Edges SHOULD carry valid_from and optional valid_to for temporal queries.
Temporal history
The graph is inherently temporal. Intelligence engines query signals as-of a point in time for audit replay:
signals(S, C, t) = { σ | σ.AFFECTS = S ∧ σ.SCOPED_TO = C ∧ σ.effective_at ≤ t ∧ ¬expired(σ, t) }
Historical replay supports dispute investigation and regulatory examination.
Trust relationships
A trust relationship is a durable edge between subjects or between subject and institution:
- Employment relationship (organization employs individual)
- Landlord-tenant relationship
- Counterparty partnership
- Community endorsement
Relationships may unlock relationship-scoped signals (e.g., employer verification) without exposing unrelated contexts.
Graph isolation
Context isolation is enforced by constraining traversals:
- Lending lookups traverse lending-scoped signals unless lens derivation rules expand scope.
- Cross-context inference MUST be explicit in lens
derivation_rules.
Query patterns
| Pattern | Use case |
|---|---|
| Neighborhood | All signals for subject in context |
| Provenance walk | Signal → event → producer |
| Path trust | Endorsement chain depth and strength |
| Coverage analysis | Detect thin subgraphs |
Federation
Federated deployments replicate subject nodes and foreign assertion edges. Conflict resolution prefers higher-confidence registry merges and signed assertion precedence.
Storage considerations
Implementations typically combine:
- OLTP store — identity and entitlement records
- Event log — immutable event stream
- Graph index — traversal-optimized signal adjacency
- Derived cache — materialized context scores