5 papers
Semi-interval Comparison Constraints in Query Containment and Their Impact on Certain Answer Computation
Foto N. Afrati, Matthew Damigos
We consider conjunctive queries with arithmetic comparisons (CQAC) and investigate the computational complexity of the problem: Given two CQAC queries, and , is contai…
Efficient query evaluation techniques over large amount of distributed linked data
Eleftherios Kalogeros, Manolis Gergatsoulis, Matthew Damigos +1
As RDF becomes more widely established and the amount of linked data is rapidly increasing, the efficient querying of large amount of data becomes a significant challenge. In this…
Evaluating Continuous Basic Graph Patterns over Dynamic Link Data Graphs
Manolis Gergatsoulis, Matthew Damigos
In this paper, we investigate the problem of evaluating Basic Graph Patterns (BGP, for short, a subclass of SPARQL queries) over dynamic Linked Data graphs; i.e., Linked Data graph…
Querying collections of tree-structured records in the presence of within-record referential constraints
Foto N. Afrati, Matthew Damigos
In this paper, we consider a tree-structured data model used in many commercial databases like Dremel, F1, JSON stores. We define identity and referential constraints within each t…
On the complexity of query containment and computing certain answers in the presence of ACs
Foto N. Afrati, Matthew Damigos
We often add arithmetic to extend the expressiveness of query languages and study the complexity of problems such as testing query containment and finding certain answers in the fr…