Are you saying that because there are 2 links, one in each direction, that it unnecessarily overly complicates the ways of querying between resources?
In regular cataloging workflow, we believe most will use:
bf:Instance bf:instanceOf bfWork;
and more rarely,
bf:Work bf:hasInstance bf:Work,
but didn’t want to preclude doing it that way.
For example, a movie comes out and the bf:Work and bf:Instance are created, and then subsequent DVD and other formats come out, which will mean more Instances pointing back to the original Work.
In fact relying on bf:hasInstance is pretty impractical in the open, because a system would have to know all the places to query that may have new Instances that point to them, and the bf:Work would become prohibitively large.
Yes, the query in the UC doc is one of the many, many possible ways to encode a title using the current vocabulary.
There is, in English rather than SPARQL:
* Work with bf:title ( http://bibframe.org/vocab/title.html )
* Instance with bf:title
* Work with bf:titleStatement ( http://bibframe.org/vocab/titleStatement.html )
* Instance with bf:titleStatement
* Work with bf:label ( http://bibframe.org/vocab/label.html ) N.B. look at the example here
* Instance with bf:label
* Work with bf:workTitle of a bf:Title
* Instance with bf:instanceTitle of a bf:Title
* Work with bf:titleVariation of a bf:Title
* Instance with bf:titleVariation of a bf:Title
* Instance with bf:abbreviatedTitle of a bf:Title
* Instance with bf:keyTitle of a bf:Title
* Multiplied by two ways to get from Work to Instance (bf:hasInstance, bf:instanceOf)
* Multiplied by the matrix of title-string-holding attributes of bf:Title:
* bf:Title uses bf:titleValue alone
* bf:Title uses bf:titleValue and bf:subtitle
* ...plus bf:partTitle, bf:partNumber, bf:titleAttribute, bf:titleQualifier
* bf:label could also be used instead of bf:titleValue
And this without translation, transliteration or the other complexities introduced in the thread's discussion.
* Presumably one could have a HeldItem/HeldMaterial with a title different from its Instance, if someone physically modified a particular copy. This isn't in the model at the moment, but thinking in an archival way rather than library way I don't see why not. I leave this as an exercise for the reader.