(Un)equality of literals

Hi all,

Although the working group probably has seized to exist now that
SPARQL has reached the Recommendation status, I hope someone can answer
the following question:

When comparing two literals with supported but unequal datatypes, should
these literals be considered to be unequal?

The following cases are clear to me:

* "2001-01-01"^^xsd:date = "2002-02-02"^^xsd:date --> false
   assuming that xsd:date comparisons are supported.

* "2001-01-01"^^xsd:date = "2001-01-02"^^ex:myDate --> type error
   since ex:myDate is an unknown/unsupported datatype.

But what would be the result of this comparison?:
"2001-01-01"^^xsd:date = "2001-01-01T00:00:00+00:00"^^xsd:dateTime

Should this:
a) return false since both datatypes are known and the values are
    considered to be uncomparable/unequal, or
b) produce a type error since the datatypes are incompatible?

Hope someone can clear this up for me.

Regards,

Arjohn Kampman

-- 
Arjohn Kampman, Senior Software Engineer
Aduna - Guided Exploration
www.aduna-software.com