---
title: "Comment by Rob Atkinson on \"JSON Schema is a constraint system\" | Hashnode"
description: "Is is worth tying these ideas into the concepts of open-world and closed-world views, and the consequent fairly natural match with RDF, and JSON-LD ?"
url: "https://hashnode.com/posts/json-schema-is-a-constraint-system/636ec3c29fcbe783317b2b8d/comment/63ef62733c9c765be7a4775d"
---

[Discussion](https://hashnode.com/posts/json-schema-is-a-constraint-system/636ec3c29fcbe783317b2b8d)

Comment [JSON Schema is a constraint system](https://hashnode.com/posts/json-schema-is-a-constraint-system/636ec3c29fcbe783317b2b8d)

[Rob Atkinson](https://hashnode.com/@ratkinson)

[Feb 17, 2023](https://hashnode.com/posts/json-schema-is-a-constraint-system/636ec3c29fcbe783317b2b8d/comment/63ef62733c9c765be7a4775d)

Is is worth tying these ideas into the concepts of open-world and closed-world views, and the consequent fairly natural match with RDF, and JSON-LD ?

[Henry Andrews](https://hashnode.com/@handrews)

[Mar 12, 2024](https://hashnode.com/posts/json-schema-is-a-constraint-system/636ec3c29fcbe783317b2b8d/comment/63ef62733c9c765be7a4775d#reply-65f08314c843953ec5b68bf5)

My understanding is that an open world allows for indeterminate truth values. Unless there's an error in the schema, it's always possible to determine whether a given instance is valid with respect to a given schema. It's just that the starting point (the empty schema) allows everything. So that would seem to me to be a closed world approach.

[David Kemp](https://hashnode.com/@davi9)

[May 22, 2024](https://hashnode.com/posts/json-schema-is-a-constraint-system/636ec3c29fcbe783317b2b8d/comment/63ef62733c9c765be7a4775d#reply-664e380e59083c7f0682ca34)

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.)