Does indeterminacy in an open world express a limitation of modeling a world, or indeterminacy in the model itself? (The map is not the territory, but given a map can truth be indeterminate?)
All sorts of vagueness exists in the real world, "Fred is bald" includes at least two: "which Fred?" and "what is bald?" But does an open world model require that subjects have a unique instance id and that the "bald" attribute is a binary type (or an integer threshold for number of hairs on the head)?
I'd assume that an open world model does not allow vagueness-based indeterminate truth (it follows the law of the excluded middle). Are there different scenarios where indeterminate truth is permitted in the model?
(Attributes can be optional, and if a subject does not have a "bald" attribute then the question cannot be answered for that subject. But that applies to both closed and open worlds.)