Verification¶

gds-business provides 11 domain-specific verification checks across three diagram types, plus access to the 6 GDS generic checks (G-001..G-006) via the unified verify() function.

Using verify()¶

The verify() function auto-dispatches to the correct domain checks based on model type:

from gds_business import verify

report = verify(model)                          # Domain + GDS checks
report = verify(model, include_gds_checks=False)  # Domain checks only
report = verify(model, domain_checks=[my_check])  # Custom checks

The returned VerificationReport contains a list of Finding objects with:

check_id — e.g., "CLD-001", "SCN-002", "G-003"
severity — ERROR, WARNING, or INFO
message — human-readable description
passed — whether the check passed
source_elements — elements involved

CLD Checks¶

ID	Name	Severity	What it checks
CLD-001	Loop polarity classification	INFO	Finds all cycles, classifies as Reinforcing (R) or Balancing (B) by counting negative links
CLD-002	Variable reachability	WARNING	Every variable appears in at least one link
CLD-003	No self-loops	ERROR	No link has source == target

CLD-001: Loop Polarity¶

This is an informational check — it doesn't fail, but reports the structure of feedback loops:

[CLD-001] ✓ Loop Population -> Births -> Population: Reinforcing (R) (0 negative link(s))
[CLD-001] ✓ Loop Population -> Deaths -> Population: Balancing (B) (1 negative link(s))

CLD-002: Variable Reachability¶

Flags isolated variables that don't participate in any causal relationship:

[CLD-002] ✗ Variable 'Unused' does NOT appear in any link

CLD-003: No Self-Loops¶

Self-loops (a variable causing itself) are structurally invalid:

[CLD-003] ✗ Self-loop detected: 'X' -> 'X'

Note

CLD-003 is also enforced at construction time by the CausalLoopModel validator. The check exists for completeness when running verify().

SCN Checks¶

ID	Name	Severity	What it checks
SCN-001	Network connectivity	WARNING	All nodes reachable via BFS from demand/supply paths
SCN-002	Shipment node validity	ERROR	source and target exist
SCN-003	Demand target validity	ERROR	target exists
SCN-004	No orphan nodes	WARNING	Every node in at least one shipment or demand

SCN-001: Network Connectivity¶

Uses BFS from demand targets to check reachability:

[SCN-001] ✗ Node 'Isolated Warehouse' is NOT reachable in the supply network

SCN-004: No Orphan Nodes¶

Nodes not connected to any shipment or demand are flagged:

[SCN-004] ✗ Node 'Unused DC' is NOT connected

VSM Checks¶

ID	Name	Severity	What it checks
VSM-001	Linear process flow	WARNING	Each step has ≤1 incoming, ≤1 outgoing material flow
VSM-002	Push/pull boundary	INFO	Identifies where flow_type transitions from push to pull
VSM-003	Flow reference validity	ERROR	All flow source/target are declared elements
VSM-004	Bottleneck vs takt	WARNING	Max cycle_time ≤ customer takt_time

VSM-001: Linear Process Flow¶

Value streams are typically linear. Branching may indicate modeling issues:

[VSM-001] ✗ Step 'Sorting': 1 incoming, 2 outgoing material flow(s) — non-linear (branching detected)

VSM-002: Push/Pull Boundary¶

Lean manufacturing distinguishes push (schedule-driven) from pull (demand-driven) flows. This check identifies transition points:

[VSM-002] ✓ Push/pull boundary at 'Welding': push->pull

VSM-004: Bottleneck vs Takt¶

The slowest process step (bottleneck) must not exceed customer takt time:

[VSM-004] ✗ Bottleneck 'Welding' (cycle_time=45.0) > customer 'End User' takt_time=40.0

GDS Generic Checks¶

When include_gds_checks=True (default), the model is compiled to SystemIR and the 6 GDS generic checks run:

ID	Name	What it checks
G-001	Domain/codomain compatibility	Wiring type tokens match
G-002	Signature completeness	Every block has inputs and outputs
G-003	Unique block naming	No duplicate block names
G-004	Wiring source existence	Wired blocks exist
G-005	Wiring target existence	Wired blocks exist
G-006	Hierarchy consistency	Block tree is well-formed

Note

G-002 will flag BoundaryAction blocks as having "no inputs" — this is expected since they are exogenous sources by design.