5 papers · 1 filter
Semijoins of Annotated Relations
Phokion G. Kolaitis
The semijoin operation is a fundamental operation of relational algebra that has been extensively used in query processing. Furthermore, semijoins have been used to formulate desir…
Gamma Acyclicity, Annotated Relations, and Consistency Witness Functions
Albert Atserias, Phokion G. Kolaitis
During the early days of relational database theory it was realized that "acyclic" database schemas possess a number of desirable semantic properties. In fact, three different noti…
Query Repairs
Balder ten Cate, Phokion Kolaitis, Carsten Lutz
We formalize and study the problem of repairing database queries based on user feedback in the form of a collection of labeled examples. We propose a framework based on the notion…
Rewriting Consistent Answers on Annotated Data
Phokion G. Kolaitis, Nina Pardal, Jonni Virtema +1
We embark on a study of the consistent answers of queries over databases annotated with values from a naturally ordered positive semiring. In this setting, the consistent answers o…
Consistency of Relations over Monoids
Albert Atserias, Phokion G. Kolaitis
The interplay between local consistency and global consistency has been the object of study in several different areas, including probability theory, relational databases, and quan…