Re: shapes-ISSUE-188 (define validation): "Validation" needs to be defined

Hi Karen,

the current snapshot defines the term "validation" in the beginning of 
section 3:

The definition forvalidatingadata graph <#dfn-data-graph>against ashapes 
graph <#dfn-shapes-graph>as well as anode <#dfn-node>from the data graph 
against ashape <#dfn-shape>from the shapes graph is provided below:

VALIDATION DEFINITION

  * Afocus node <#dfn-focus-node>validates against ashape <#dfn-shape>if
    and only if either it does not validate against somefilter
    <#dfn-filter>of the shape or none of theconstraints
    <#dfn-constraint>in the shape produce avalidation result
    <#dfn-validation-results>or afailure <#dfn-failure>for the focus node.
  * Adata graph <#dfn-data-graph>validates against ashape <#dfn-shape>if
    and only if each node that is in any of thetargets <#dfn-target>of
    the shape validates against the shape.
  * Adata graph <#dfn-data-graph>validates against ashapes graph
    <#dfn-shapes-graph>if and only if the data graph validates against
    eachshape <#dfn-shape>in the shapes graph.

I believe this covers the terminology, esp with the different nuances of 
validation, e.g. of a focus node. It also correctly identifies failures 
as another possible outcome.

Your proposal merely bases validation on another undefined term "obeys 
the constraints", which IMHO just shifts the problem. The ultimate 
definition may require an elaborated link to the evaluation mechanisms 
including SPARQL queries, but Dimitris' prose above clarifies that 
eventually it's about not producing any validation results and failures.

What is missing for this ISSUE?

Holger


On 9/10/2016 12:51, RDF Data Shapes Working Group Issue Tracker wrote:
> shapes-ISSUE-188 (define validation): "Validation" needs to be defined
>
> http://www.w3.org/2014/data-shapes/track/issues/188
>
> Raised by: Karen Coyle
> On product:
>
> The term validation as used in SHACL needs to be defined. (The English language term is ambiguous.) The XML schema has a clear defiinition [1]. Based on that, I suggest the following as a definition of validation in SHACL:
>
> [Definition:]   Validation is the process of determining whether a node in the data graph obeys the constraints expressed in a shapes graph. The validation result is true when the node in the data graph obeys the constraints, and false when it does not.
>
> Note that XML allows for 3 validation results: true, false, and undetermined. I do not know if SHACL also follows this pattern, so my true/false declaration above may need adjustment if that is the case. Here is what XML schema says:
>
> Note: As just defined, validation produces not a binary result, but a ternary one: if the information item is ·strictly assessed·, it will be either valid or invalid, but if no applicable declaration is found, its validity will be unknown (and its [validity] property will have the value notKnown). Whether in a particular application notKnown should be treated in the same way as invalid or differently is outside the scope of this specification; sometimes one choice is appropriate, sometimes the other.
>
>
> [1] See: https://www.w3.org/TR/2012/REC-xmlschema11-1-20120405/#key-vn
>
>
>