xsd:dateTime less than operator issue

[wrobell]

Filters on xsd:dateTime work with literals, i.e.

FILTER(?start > "2016-01-01 20:01"^^xsd:dateTime)

But if there are two variables of xsd:dateTime then filter does not work properly, i.e.

FILTER(?start < ?end)

Script illustrating the issue below. It should show c1 and c2 entities, but nothing is shown instead.

from pprint import pprint
import rdflib
import io

data = """
@prefix : <#>.
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>.
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>.
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.

:C a rdfs:Class.

:start a rdf:Property;
    rdfs:domain :C; 
    rdfs:range xsd:dateTime.

:end a rdf:Property;
    rdfs:domain :C; 
    rdfs:range xsd:dateTime.

:c1 a :C;
    :start "2016-01-01 20:00:00"^^xsd:dateTime;
    :end "2016-01-02 20:01:00"^^xsd:dateTime.

:c2 a :C;
    :start "2016-01-01 20:05:00"^^xsd:dateTime;
    :end "2016-01-01 20:30:00"^^xsd:dateTime.
"""

graph = rdflib.Graph()

f = io.StringIO(data)
graph.parse(f, format='n3')

result = graph.query("""
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>

SELECT ?c
WHERE {
    ?c :start ?start;
        :end ?end.
#    FILTER(?start > "2016-01-01 20:01"^^xsd:dateTime)   # this works!
    FILTER(?start < ?end)
}
""")

pprint(list(result))

[colinfang]

Equality operator doesn't work either.

g2 = rdflib.Graph()
literal_date = Literal(datetime.date(2016,1,1), datatype=XSD.date)
print g2.serialize(format="n3")
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix xml: <http://www.w3.org/XML/1998/namespace> .
@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<1> <1> "2016-01-01"^^xsd:date .

q = """
    Ask {
        ?x ?x ?dt .
        FILTER (?dt = ?dt2) .
    }
    """
res = g2.query(
    q, initBindings={
        'dt2': literal_date
    }
).askAnswer
res

False

[gromgull]

Your first case, the problem is that your datetime syntax is wrong, if you change it to:

    :c1 a :C;
        :start "2016-01-01T20:00:00"^^xsd:dateTime;
        :end "2016-01-02T20:01:00"^^xsd:dateTime.

    :c2 a :C;
        :start "2016-01-01T20:05:00"^^xsd:dateTime;
        :end "2016-01-01T20:30:00"^^xsd:dateTime.

it works.

The second problem is #615