Meeting minutes
DICOM
dbooth: Erich added more options to consider, based on DICOM XML conversion
erich: Extra triples matter with large DICOM data.
… Everything in DICom is a list, even if the multiplicity is only one. It adds another triples.
dbooth: Even though the Turtle lists look more concise to a human, they don't actually reduce the nubmer of triples from having an explicit index like in option 7
erich: But the Turtle lists allow you to use convenient list tooling.
dbooth: Options 8, 9a and 9b. if that dcm:UNK is in the slot for someone's birthdate, then if you used dcm:UNK for both Sally and Bob, you are asserting that they have the same birthdate.
eric: The use of dcm:UNK costrains you to predicates that have a range that includes both the values you want, and another value
… that represents the missing value.
… When you have values that are outside the intuitive range of the predicate, then you have changed the range of predicate.
eric: When the range is either a birthdate or 3 null flavors, then your sparql query needs to account for the null flavors.
dbooth: This looks to me like a viable approach.
… Other thoughts?
erich: I'm fine either way, with bnodes or not.
detlef: I prefer simpler.
… And prefer dcm:UNK, because it's easier to check than "UNK"^^dcm:nullFlavor
eric: If you use the bnode standoff for nulls then you can leverage inference more easily.
eric: What if you have an owl datatype property, and use a bnode as a value. Is that legal?
dbooth: IDK. Need to ask Jim Balhoff
detlef: I think it's not allowed in OWL DL
eric: One axis: IRI vs special literal vs bnode standoff
… Another axis: Whether we have an rdf:value standoff.
dbooth: Need to find out about OWL impact
ACTION: DBooth to ask Jim Balhoff about OWL impact of the different options.
erich: Right now we're constructing using dcm:34567 or dcm:theKeyword . Either would be fine, but one is more human readable.
eric: Religious war: Some people think you should use non-readable URIs, so that label can be updated.
erich: In DICOM the keyword names are unchangeable.
… therefore they can be used in the IRIs.
… and numeric IRI would be owl:sameAs the keyword IRI.
detlef: Out next week. Back in two weeks.
ADJOURNED
rssagent, draft minutes
dbooth: OPTIONS 8, 9a and 9b. if that dcm:UNK is in the slot for someone's birthdate, then if you used dcm:UNK for both Sally and Bob, you are asserting that they have the same birthdate.
eric: The use of dcm:UNK constrains you to predicates that have a range that includes both the values you want, and another value
… that represents the missing value.
… When you have values that are outside the intuitive range of the predicate, then you have changed the range of predicate.
eric: When the range is either a birthdate or 3 null flavors, then your sparql query needs to account for the null flavors.
dbooth: Okay, so for a birthdateOrNull predicate, when the value is null, it is not actually asserting anything about that person's birthdate. Interesting.
dbooth: This looks to me like a viable approach.
… Other thoughts?
erich: I'm fine either way, with bnodes or not.
detlef: I prefer simpler.
… And prefer dcm:UNK, because it's easier to check than "UNK"^^dcm:nullFlavor
eric: If you use the bnode standoff for nulls then you can leverage inference more easily.
eric: What if you have an owl datatype property, and use a bnode as a value. Is that legal?
dbooth: IDK. Need to ask Jim Balhoff
detlef: I think it's not allowed in OWL DL
eric: One axis: IRI vs special literal vs bnode standoff
… Another axis: Whether we have an rdf:value standoff.
dbooth: If you have an rdf:value standoff then you can skip having an explicit null, because you can just omit the rdf:value triple when it is null.
dbooth: Need to find out about OWL impact of either using a bnode in an otherwise list of primitives/literals; or using something like dicom:null in an otherwise list of literals. You wouldn't be able to say that the dicom:null is owl:differentFrom any of the actual dates, because today you might only know that Sally has a birthdateOrNull of dicom:null, but tomorrow you might find an assertion saying that Sally has a birthdateOrNull of 1990-12-31 . .
. .
CORRECTION ADDED LATER by dbooth: No, that's wrong. It isn't about owl:differentFrom. It's about the multiplicity of the birthdateOrNull predicate. It needs to allow more than one value, so that it can both have a dicom:null value and a 1990-12-31 value, even if it isn't allowed to have two different actual date values.
ACTION: DBooth to ask Jim Balhoff about OWL impact of the different options.
erich: Right now we're constructing using dcm:34567 or dcm:theKeyword . Either would be fine, but one is more human readable.
eric: Religious war: Some people think you should use non-readable URIs, so that labels can be updated.
erich: In DICOM the keyword names are unchangeable, as are the numbers.
… therefore they can be used in the IRIs.
… and numeric IRI would be owl:sameAs the keyword IRI.
detlef: Out next week. Back in two weeks.
ADJOURNED
rssagent, draft minutes