fix known errors identified by SPARQL Exists Community Group

[pfps]

There are several known errors in this document that should be fixed.

[hartig]

Are you referring to the errata at https://www.w3.org/2013/sparql-errata or to other errors? If it is the former, @afs mentioned that he will create issues for them here in the repo and then we can start addressing them in the document. If you mean other errors, however, it would be helpful if you could create a separate issue for each of the errors that you have in mind, including a detailed description of the error and/or a pointer to an external source that describes the error.

[pfps]

There are a number of errors in the SPARQL query recommendation that cause undefined or bad behaviour. Implementations differ in what they do in some of these cases.

See the output of the SPARQL exists community group.

https://www.w3.org/community/sparql-exists/
https://w3c.github.io/sparql-exists/docs/sparql-exists.html

I'm creating this umbrella issue so that there can be a discussion of which of these errors should be fixed, if any.

[hartig]

Okay, then let's use this issue here for the moment to collect such errors, but I would like to avoid intermixing this collection thread also with discussions specific to some of these errors. For such discussions, there should be separate issues per error (or per group of related errors).

So, are there other such documented errors that you (or anyone else here) are aware of?

[afs]

See also https:/w3c/sparql-12/blob/main/SEP/SEP-0007/sep-0007.md

EXISTS is a special case.

See also SQL for the history of correlated subqueries.