Recognises a cardinality rule stated from one end only
A cardinality rule stated from one end, leaving the other end unconstrained. The commonest cause of duplicates.
Can AI do this?
People still lead Few or none of the tested AI models showed they master this. 0 of 4 models in the current benchmark master it.
| Model | Tier | Probability of mastery | Status |
|---|---|---|---|
| gemini-4-argon | Flagship | 76% | Not shown |
| gemini-3.1-pro-preview* | Flagship | 99% | Mastered |
| gpt-6-astra* | Flagship | 100% | Mastered |
| claude-fable-5-1* | Flagship | 100% | Mastered |
| gemini-3.8-flash* | Mid tier | 99% | Mastered |
| gpt-6.1-sol* | Mid tier | 99% | Mastered |
| claude-sonnet-5-5* | Mid tier | 99% | Mastered |
| gemini-3.5-flash-lite | Low cost | 44% | Not shown |
| gpt-6-luna | Low cost | 75% | Not shown |
| claude-haiku-5-5 | Low cost | 74% | Not shown |
* From the earlier benchmark of 2026-10: 10 data-modelling test tasks, 3 runs per task, graded by claude-opus-5-5. These models have not taken the current 123 tasks yet; the two methods differ, so compare their figures with care. They are left out of the “most models” counts and the best-model picks.
Mastered means a probability of at least 90% that the model has this knobit, estimated from its graded answers. “Not shown” means the answers do not settle it either way. How the models are tested.
What it looks like in practice
Expected result: The unconstrained end and the rule for it
How it is assessed: Flags the deficient case and passes the acceptable one. Deficient: "Each account has exactly one IBAN" (nothing stops two accounts sharing one) Acceptable: Both: "each account has exactly one IBAN" and "each IBAN is held by at most one account"
Also known as: One direction only (data rule)
Related knobits
Builds on
All 23 knobits of Document data rules in SBVR.
Source: Review checklist 02-data-rules (data-quality), row 18; formerly data-modelling K-318