The complexity of social coordination

Konstantinos Mamouras, Sigal Oren, Lior Seeman, Lucja Kot, Johannes Gehrke

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Coordination is a challenging everyday task; just think of the last time you organized a party or a meeting involving several people. As a growing part of our social and professional life goes online, an opportunity for an improved coordination process arises. Recently, Gupta et al. proposed entangled queries as a declarative abstraction for data-driven coordination, where the difficulty of the coordination task is shifted from the user to the database. Unfortunately, evaluating entangled queries is very hard, and thus previous work considered only a restricted class of queries that satisfy safety (the coordination partners are fixed) and uniqueness (all queries need to be satisfied). In this paper we significantly extend the class of feasible entangled queries beyond uniqueness and safety. First, we show that we can simply drop uniqueness and still efficiently evaluate a set of safe entangled queries. Second, we show that as long as all users coordinate on the same set of attributes, we can give an efficient algorithm for coordination even if the set of queries does not satisfy safety. In an experimental evaluation we show that our algorithms are feasible for a wide spectrum of coordination scenarios.

Original languageEnglish
Pages (from-to)1172-1183
Number of pages12
JournalProceedings of the VLDB Endowment
Issue number11
StatePublished - 1 Jan 2012
Externally publishedYes

ASJC Scopus subject areas

  • Computer Science (miscellaneous)
  • Computer Science (all)


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