In their paper, the authors have proven some undesirable complexity results, leading to undesirable performance when evaluating certain path queries in SPARQL1.1 according to the semantics in the Last Call working draft published by the SPARQL Working group in January 2012.
While we acknowledge that scientific papers may use provocative titles, as a more constructive way of feedback the authors have also used the W3C comments mechanism to engage directly with the working group on the issue. The working group has discussed the issue, and arrived at an alternative design of the semantics avoiding the problematic complexity of the original one. The re-design will be part of an upcoming, revised 2nd Last Call working draft of the SPARQL 1.1 Query Language—a proof that the W3C’s process works and that feedback, also from outside the working groups, is considered as important to arrive at robust and widely adopted standards.
Apart from property paths, SPARQL 1.1 will add various other new and useful features (such as aggregation, negation, subqueries, updates, entailment regimes, …) that were demanded by the community and collected in the working group in an initial feature gathering phase. Feedback to the W3C SPARQL working group on its current drafts is welcome to be sent to email@example.com.