Re: sh:uniqueLang "1"^^xsd:boolean .

> My problem is that I’m using RDF4J to parse the turtle file in the
> test, and when I do the following:
>
> boolean uniqueLang = ((Literal) object).booleanValue();
>
> It returns true. Because “1”^^xsd:Boolean means the same as
> writing true.

Jena does the same -  the "value" is the XSD concept of value - point in
the value space.

To add one small thing to Simon's message:

In a SPARQL FILTER, "1"^^xsd:boolean = "true"^^xsd:boolean

but sameTerm("1"^^xsd:boolean, "true"^^xsd:boolean) is false.

sameTerm compares RDF terms by their three parts.

java.equals has to be like sameTerm if the graph preserve the difference of:

:s :p "1"^^xsd:boolean .
:s :p "true"^^xsd:boolean .

Two triples.

    Andy

On Tue, 26 Mar 2019 at 06:42, Simon Steyskal <simon.steyskal@wu.ac.at>
wrote:

> Hi!
>
> > In a SPARQL filter, is “1”^^xsd:Boolean == true? Like
> > “0001”^^xsd:integer == “1”^^xsd:integer.
>
> yes (with lowercase B though -> xsd:boolean) :
>
> http://sparql-playground.sib.swiss/?query=select%20%3Fperson%20%3Fpet%20where%20%7B%0A%20%20%7B%0A%20%20%20%20%3Fperson%20rdf:type%20dbo:Person%20.%0A%09%3Fperson%20tto:pet%20%3Fpet%20.%0A%20%20FILTER(%221%22%5E%5Exsd:boolean%20%3D%20true)%20.%0A%09%7D%0A%20%20UNION%0A%20%20%20%20%7B%0A%20%20%20%20%3Fperson%20rdf:type%20dbo:Person%20.%0A%09%3Fperson%20tto:pet%20%3Fpet%20.%0A%20%20FILTER(%220%22%5E%5Exsd:boolean%20%3D%20false)%20.%0A%09%7D%0A%20%20%20%20UNION%0A%20%20%20%20%7B%0A%20%20%20%20%3Fperson%20rdf:type%20dbo:Person%20.%0A%09%3Fperson%20tto:pet%20%3Fpet%20.%0A%20%20FILTER(%222%22%5E%5Exsd:boolean%20%3D%20true)%20.%0A%09%7D%0A%7D&output=html
>
> > And are they isomorphic?
>
> fwiw, the old RDF 1.0 REC had an example about the differences between
> value space and lexical space using xsd:boolean ->
> https://www.w3.org/TR/rdf-concepts/#section-Datatypes-intro
> in the new RDF 1.1 specification there's
> https://www.w3.org/TR/rdf11-concepts/#section-Graph-Literal:
> ----
> Literal term equality: Two literals are term-equal (the same RDF
> literal) if and only if the two lexical forms, the two datatype IRIs,
> and the two language tags (if any) compare equal, character by
> character. Thus, two literals can have the same value without being the
> same RDF term. For example:
>
>        "1"^^xs:integer
>        "01"^^xs:integer
>
> denote the same value, but are not the same literal RDF terms and are
> not term-equal because their lexical form differs.
> ----
>
> which would in theory also hold for:
>
>        "1"^^xsd:boolean
>        "true"^^xsd:boolean
>
> as their lexical form  differs.. However, according to a footnote in
> https://www.w3.org/TR/sparql11-query/#func-RDFterm-equal: "Invoking
> RDFterm-equal on two typed literals tests for equivalent values. "
> -> Hence FILTER("0"^^xsd:boolean = false && "1"^^xsd:boolean = true &&
> "1"^^xsd:boolean = "true"^^xsd:boolean) is true, while
> FILTER("2"^^xsd:boolean = true || "01"^^xsd:boolean = true) is not.
>
> hth, simon
>
>
> ---
> DDipl.-Ing. Simon Steyskal
> Institute for Information Business, WU Vienna
>
> www: http://www.steyskal.info/  twitter: @simonsteys
>
> Am 2019-03-26 06:43, schrieb Håvard Ottestad:
> > Hi,
> >
> > Thank you for the good comments.
> >
> > My problem is that I’m using RDF4J to parse the turtle file in the
> > test, and when I do the following:
> >
> > boolean uniqueLang = ((Literal) object).booleanValue();
> >
> > It returns true. Because “1”^^xsd:Boolean means the same as
> > writing true.
> >
> > In a SPARQL filter, is “1”^^xsd:Boolean == true? Like
> > “0001”^^xsd:integer == “1”^^xsd:integer.
> >
> > And are they isomorphic?
> >
> > Håvard
> >
> > On 25 Mar 2019, at 23:31, Holger Knublauch <holger@topquadrant.com>
> > wrote:
> >
> >> On 26/03/2019 8:01 am, Andy Seaborne wrote:
> >>
> >> Håvard - in what way does "1"^^xsd:boolean in uniqueLang-002 cause
> >> specific problems? I can think of several! including the fact it
> >> does really need the comment to be read.
> >>
> >> On Mon, 25 Mar 2019 at 19:31, Håvard Ottestad
> >> <hmottestad@gmail.com> wrote:
> >>
> >> I don’t feel that SHACL gets to dictate syntax. Shapes can be
> >> represented in any language, jsonld, rdfxml or turtle.
> >>
> >> Agreed - any language for shapes.
> >>
> >> Here is my spec reading: (not advocacy one way or the other, just
> >> trying to dig into what the spec says)
> >>
> >> true denotes the RDF term "true"^^xsd:boolean. false denotes the
> >> RDF term "false"^^xsd:boolean.
> >>
> >> so true  means the RDF term with lexical form "true" and datatype
> >> xsd:boolean. That is conflating Turtle syntax here. It would look
> >> different in JSON-LD.
> >>
> >> My guess is that this true is used because it makes triple matching
> >> without XSD-value interpretation work.
> >
> > Yes, at the time it sounded like it makes implementations easier.
> > Meanwhile, several people ran into this issue though, so maybe it
> > wasn't the best decision to only support true. It arguably also wasn't
> > the best decision by XSD to also support "1", but I guess when you
> > pile technologies on top of each other then those downstream have to
> > live with the consequences...
> >
> > I am also keen to hear what the specific problem is though, and why a
> > work-around is difficult. Adjusting the spec for a SHACL 1.1 would
> > likely require an incompatible change, and it still feels like a minor
> > scenario to me.
> >
> > Holger
> >
> >>> If “1”^^xsd:Boolean is the syntax equivalent to true; then
> >>> it’s not up to the SHACL spec to specify which one is allowed.
> >>
> >> It is not equivalent, not the same RDF term. Like
> >> "+001"^^xsd:integer is a different RDF term from "1"^^xsd:integer.
> >>
> >> Maybe that comment in uniqueLang-0002 has historical significance.
> >>
> >> It seems to say the shape has no constraint.
> >>
> >> Andy
> >>
> >> Håvard
> >>
> >> On 25 Mar 2019, at 20:24, Andy Seaborne
> >> <andy.seaborne@topquadrant.com> wrote:
> >>
> >> In the technical sense of SHACL? (It's legal Turtle)
> >>
> >> The test has a comment in it:
> >>
> >> # Note that the value above is "1"^^xsd:boolean, which is distinct
> >> from "true"^^xsd:boolean.
> >> # Only true is mentioned in the spec, meaning that "1" will not
> >> activate the constraint
> >> # and the constraint is being ignored.
> >>
> >> which goes with the SHACL spec saying:
> >>
> >> The property sh:uniqueLang can be set to true to specify that no
> >> pair of value nodes [1] may use the same language tag.
> >>
> >> and
> >>
> >> sh:uniqueLang
> >> true to activate this constraint.
> >>
> >> it's not SHACL-true so this is not active.
> >>
> >> I'm hesitant to say "invalid syntax" because it begs the question of
> >> "which syntax?"
> >>
> >> On Mon, 25 Mar 2019 at 18:36, Håvard Ottestad
> >> <hmottestad@gmail.com> wrote:
> >>
> >> Hi Andy,
> >>
> >> Thanks for chiming in.
> >>
> >> Do you feel that "1"^^xsd:boolean should be invalid syntax?
> >>
> >> Håvard
> >>
> >> On 25 Mar 2019, at 19:12, Andy Seaborne
> >> <andy.seaborne@topquadrant.com> wrote:
> >>
> >> On Mon, 25 Mar 2019 at 16:56, Håvard Ottestad
> >> <hmottestad@gmail.com> wrote:
> >>
> >> Hi,
> >>
> >> I came across this little bugger in the test-suite and I would like
> >> to propose to have it removed.
> >>
> >> I’m talking about the uniqueLang-002 test which contains:
> >> sh:uniqueLang "1"^^xsd:boolean .
> >>
> >> The W3C RDF Turtle 1.1 spec mentions that there are only two legal
> >> values for booleans (true or false):
> >> https://www.w3.org/TR/turtle/#booleans
> >>
> >> That is referring to the short forms true and false in syntax.
> >>
> >> The Turtle spec ought really to say which RDF term it is short for;
> >> the canonical form being the obvious choice.
> >> (It is supposed to be the same as SPARQL sec 4.1.2 - seems the text
> >> didn't get copied over.)
> >>
> >> It links to the XML Schema definition of xsd:boolean where there are
> >> four legal syntax values for boolean: true, false, 1, 0
> >>
> >> It furthermore states that there are only two canonical values for
> >> boolean: true, false
> >>
> >> https://www.w3.org/TR/xmlschema-2/#boolean
> >>
> >> The definition in the SHACL spec is as follows:
> >> ###########
> >> If $uniqueLang is true then for each non-empty language tag that is
> >> used by at least two value nodes, there is a validation result.
> >>
> >> ###########
> >>
> >> My argument is that, unless the SHACL spec specifies the syntactical
> >> representation of the boolean, then it is moot to have a test that
> >> checks the syntax rather than the semantics.
> >>
> >> I agree that  "true"^^xsd:boolean or true should be used in line
> >> with the end of sec 1.2
> >>
> >> Andy
> >>
> >> Regards,
> >> Håvard M. Ottestad
> >> (developer of the RDF4J incremental SHACL engine)
> >
> >
> >
> > Links:
> > ------
> > [1] https://www.w3.org/TR/shacl/#dfn-value-nodes
>
>