* The authors received communication that convincingly argued this
draft in its current state does not engage sufficiently with prior work on
partially intervenable causal models. Thus, it is not yet ready to be
publicly shown in its current state Access Paper or Ask Questions
* 15 pages. This arXiv version is slightly updated relative to the
version in UAI proceedings. (Theorem 5 and Proposition 8 have been
strengthened, with Appendix C revised correspondingly. Appendix D has been
added.) Access Paper or Ask Questions