A Online Appendix to Generating Plans from Proofs

We prove results concerning the equivalence of several languages for describing queries that are implementable using access methods. Recall that a conjunctive query Q with atoms A1 . . . An is executable relative to a schema with access patterns if there is an annotation of each atom Ai = Ri(~xi) with an access method mti on R such that for each variable x of Q, for the first Ai containing x, x occurs only in an output position of mti. A UCQ ∨ iQi where Qi is a CQ is said to be executable if each disjunct is executable. Recall that in the body we proved that: