ISSUE-65: Consistency and cohesiveness of nomenclature (e.g., shapes, scopes, and constraints)

nomenclature consistency

Consistency and cohesiveness of nomenclature (e.g., shapes, scopes, and constraints)

State:

CLOSED

Product:

SHACL Spec

Raised by:

Peter Patel-Schneider

Opened on:

2015-06-01

Description:

This issue is being kept open to track other issues related to nomenclature and consistency in SHACL. The links to other issues are being kept on a separate Wiki page https://www.w3.org/2014/data-shapes/wiki/ISSUE-65:_Nomenclature


The current version of the Shapes Constraint Language (SHACL) document, at
https://w3c.github.io/data-shapes/shacl/, does not have a clear definition of a shape, a scope, or a constraint.

Here are some things that the document says about shapes, scopes, and constraints:


Shape
WRONG - "describes a group of constraints with the same focus node"
WRONG - "is a group of constraints that have the same focus node"
- Ignores scope aspect of shapes.
- Misleading about the role of a focus node.

Closed Shape
? - closed shape as one of the "other shape-based constraints"
- Is closed shape a constraint?

Scope
AMBIGUOUS - "pre-conditions that must hold before a constraint is applied to
a given focus node"
- No notion of constraint application defined in document.
- Scope is used on both shapes and constraints.

Class Scope -
AMBIGUOUS - "apply to all instances of these linked classes"
- What is an instance of a class?

Constraint
WRONG - "a condition that can be validated against a graph"
WRONG - "defines restrictions on the structure of an RDF graph"
- Most constraints are validated against a graph and a node in the graph.
WRONG - "evaluated against a focus node"
- Not for global constraints.

Global Constraint
- Different from other constraints as they don't have a real scope.

I propose that shapes, scopes, and constraints be given a firm and clear structure, along the lines of:

A shape has either a query or a scope, a set of constraints, and whether or not the shape is closed.

A scope picks out some of the nodes in an RDF graph for validation against the constraints of the shape.

A constraint forms a condition that a node in an RDF graph must satisfy to satisfy the constraint.

Related Actions Items:

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Related emails:

1. ISSUE-65 and ISSUE-111: Could IMHO be closed (from holger@topquadrant.com on 2016-07-07)
2. Re: Some ISSUE proposals for this week (from holger@topquadrant.com on 2016-04-28)
3. Re: Some ISSUE proposals for this week (from lehors@us.ibm.com on 2016-04-27)
4. Some ISSUE proposals for this week (from holger@topquadrant.com on 2016-04-27)
5. Re: RDF Data Shapes WG Agenda for 17 March 2016 (from lehors@us.ibm.com on 2016-03-17)
6. Re: RDF Data Shapes WG Agenda for 17 March 2016 (from pfpschneider@gmail.com on 2016-03-17)
7. Re: ISSUE-65: type and instance and subclass in SHACL documents (from pfpschneider@gmail.com on 2016-03-11)
8. Re: ISSUE-65: type and instance and subclass in SHACL documents (from irene@topquadrant.com on 2016-03-10)
9. Re: ISSUE-65: type and instance and subclass in SHACL documents (from kontokostas@informatik.uni-leipzig.de on 2016-03-10)
10. ISSUE-65: type and instance and subclass in SHACL documents (from holger@topquadrant.com on 2016-03-10)
11. Re: connecting ISSUE-65 (Nomenclature) to other issues (from arthur.ryman@gmail.com on 2015-11-19)
12. Re: connecting ISSUE-65 (Nomenclature) to other issues (from pfpschneider@gmail.com on 2015-11-19)
13. Re: connecting ISSUE-65 (Nomenclature) to other issues (from arthur.ryman@gmail.com on 2015-11-19)
14. connecting ISSUE-65 (Nomenclature) to other issues (from pfpschneider@gmail.com on 2015-11-12)
15. Re: RDF Data Shapes Agenda for 20 August 2015 (from lehors@us.ibm.com on 2015-08-20)
16. Re: RDF Data Shapes Agenda for 20 August 2015 (from holger@topquadrant.com on 2015-08-20)
17. Re: RDF Data Shapes Agenda for 20 August 2015 (from pfpschneider@gmail.com on 2015-08-19)
18. Re: nomenclature in current document - ISSUE-65 (from holger@topquadrant.com on 2015-08-14)
19. Re: nomenclature in current document - ISSUE-65 (from holger@topquadrant.com on 2015-08-14)
20. Re: nomenclature in current document - ISSUE-65 (from pfpschneider@gmail.com on 2015-08-13)
21. nomenclature in current document - ISSUE-65 (from pfpschneider@gmail.com on 2015-08-13)
22. Re: on constraints (ISSUE-65) (from holger@topquadrant.com on 2015-06-08)
23. Re: on constraints (ISSUE-65) (from lehors@us.ibm.com on 2015-06-05)
24. Re: on constraints (ISSUE-65) (from pfpschneider@gmail.com on 2015-06-05)
25. Re: on constraints (ISSUE-65) (from holger@topquadrant.com on 2015-06-05)
26. on constraints (ISSUE-65) (from pfpschneider@gmail.com on 2015-06-04)
27. on constraints (ISSUE-65) (from pfpschneider@gmail.com on 2015-06-04)
28. Re: shapes-ISSUE-65 (shapes, scopes, and constraints): A consistent and cohesive definition of shapes, scopes, and constraints [SHACL Spec] (from holger@topquadrant.com on 2015-06-02)
29. shapes-ISSUE-65 (shapes, scopes, and constraints): A consistent and cohesive definition of shapes, scopes, and constraints [SHACL Spec] (from sysbot+tracker@w3.org on 2015-06-01)

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