Verbalizing Ternary Fact type with 2 roles spanning uniqueness constraint

[SergeValera]

Bonjour Matt,

Verbalizing the ternary fact type reads: "For each subservice user and request type,
that subservice user uses at most one EXPL script to acknowledge the start of execution for that request type."
Why stating "at most one EXPL script" when my understanding is that to have a valid population, all roles are always populated ? why not verbalizing "exactly one EXPL script"?

Long time I wish to ask this question ! Thanks for the feedback ...

[mcurland]

I believe 'exactly one' here instead of 'at most one' would indicate that the PTVCondition objectified fact type must be populated for every combination of RequestType and SubserviceUser, which isn't implied by the model.

[TerryHalpin]

Matt is correct. "For each subservice user and request type" means "For each instance of SubServiceUser, and each instance of RequestType", so is not confined to (SubServiceUser, RequestType ) instances populating the end roles of the ternary fact type.

[jpwijbenga]

Agree with Matt and Terry. Maybe Serge is reading this implied scope:
For each subservice user and request type who participate in the same fact instance of fact type 'PTVCondition'
that subservice user uses exactly one EXPL script to acknowledge the start of execution for that request type."

Where the current NORMA reading can be more verbosely stated as :
For each subservice user and request type that exist in the entire population
that subservice user uses exactly one EXPL script to acknowledge the start of execution for that request type.