I have been using SPARQL CONSTRUCT for ontology mapping. One of the problems, I have encountered during my work is, how do I get around BNode in the output graph, as BNode are ugly, not shareable (if thats right word!) and you can say not at all useful here. What you want in the target graph is a clear URI, as you might want to share this new URI with other graphs you extract from different source ontologies.
I stumbled on this post, which have similar conclusion. Somewhere in the post the author mentions that,
"it appears to be impossible to create new URIs for the resources in the target ontology - only bnodes can be created on the fly."
and they had to use some post-processing script to manage bnodes. I am still working on finding a workaround, if I can not then I will have to conclude the same.
Based on my findings, I will update this post soon....
