1. Procedural and declarative database update languages;Abiteboul,1988
2. Generic computation and its complexity;Abiteboul,1991
3. An introduction to inductive definitions;Aczel,1977
4. Universality of data retrieval languages;Aho,1979
5. Reachability is harder for directed than for undirected finite graphs;Ajtai;J. Symbolic Logic,1990