[dotNetRDF-Develop] SPARQL and ill-formatted dates

[Tomasz P. <tom...@gm...>]

Hi Rob

We've just encountered an interesting case with parsing dates in
SPARQL queries. Initially I though it was dotNetRDF's fault, but in
the end it turned out I failed to notice we used invalid date format
and it worked while in Polish locale but failed on a German machine.

What it reveals however is that dotNetRDF is forgiving in terms of ate
formatting. Our query used a date like "04/20/2014"^^xsd:date and
compared it to some dates in the graph. The comparison works in Polish
and English locale yielding expected results. Is the processor trying
to fall back to local settings if the date isn't a valid xsd format?

If so it causes a weird state where invalid query can actually produce
false-positive results. Hence I think that we should be more strict
about date format. Or maybe it is a behaviour that SPARQL defines?

Thanks,
Tom