14:55:39 RRSAgent has joined #hcls 14:55:43 logging to https://www.w3.org/2024/05/30-hcls-irc 14:55:43 rrsagent, make logs public 15:10:09 Topic: DICOM 15:11:17 eric: Anytime you have a null, in programming you have to do a dance to get around it, because if Sally and Bob both have null in the birthdate predicate, you have to use a null guard in your code, to exclude the case when the value is a fhir:null sentinal. 15:11:52 .. .But if you use a bnode, SPARQL won't treat them as the same. So that's a benefit of using a bnode for SPARQL in that case. 15:12:33 jim: bnode seems like a good thing, but I don't think you can have a union of a an object type and a datatype. 15:13:22 ... We couldn't use a bnode for the null if it's a datatype property. 15:13:57 eric: Because in DL datatype and object properties are disjoint. 15:14:36 ... We tend to use lists when we want to round trip, and want to use sentinal types, so the transfer representation becomes something we can't reason over. 15:14:56 ... Because we have RDF lists, we're already outside of what works well in OWL. 15:16:09 jim: Could always use a bnode standoff: [ rdf:value 45 ], [ rdf:value fhir:null ]. 15:16:47 eric: Maybe we need a transform for OWL, one optimized for query and one for inference. 15:18:03 eric: Already optimized more for SPARQL. 15:18:11 dbooth: Already going down that path. 15:20:10 dbooth: What do you think would be easiest to process, Erich? 15:20:42 erich: Interesting: 15:20:42 https://github.com/awslabs/SPARQL-CDTs 15:20:42 https://awslabs.github.io/SPARQL-CDTs/spec/latest.html 15:38:10 (Discussion about CDT) 15:41:03 eric: If we had a dataset with 2 graphs g1 and g2, and they shared a bnode, _:b1 , they could be written out, g1 as RDFXML and g2 as Turtle. When you parse them again, you'd tell the parser to unify the _:b1 to reconstruct the orignal dataset. 15:44:54 eric: There isn't a way to indicate which bnodes should be treated as the same (in the same dataset) and which shold be renamed. 15:46:41 erich: CDT could be used to represent all the DICOM list data. Or do it only when literal lists -- a hybrid approach. 15:46:55 ... If this is adopted, does it replace RDF lists? 15:48:01 eric: If it is, it would take years for it to have traction. 15:49:26 erich: Anything done now cannot do CDT, because it's just a proposal. So we still need a null solution. 15:49:42 ... Rather work w what we have today. CDT is potential future direction. 15:49:58 ... But need something that's supported now, as a standard. 15:50:36 ... DICOM literal lists (whcih may have nulls) are the only problem area. 15:51:38 dbooth: This is reminding me that the ladder of RDF lists is really the wrong way to do lists. Numeric indexes is the right way to do them. 15:52:33 ... And they should be called arrays, not lists. 15:52:41 .. .It's longstanding big hole in RDF. 15:54:19 erich: I have a DCM to RDF converter that I've used for a while. But never handled nulls. 15:55:48 ... Plan to release it as open source, but will leave a placeholder for the null issue. 15:56:30 eric: We care about an RDF rather than having a bnode hidden inside a literal. 16:01:03 Present: EricP, Erich Bremer, Gaurav Vaidya, Jim Balhoff, David Booth 16:01:08 ADJOURNED 16:01:12 rrsagent, draft minutes 16:01:14 I have made the request to generate https://www.w3.org/2024/05/30-hcls-minutes.html dbooth