Human-assisted graph search: It's okay to ask questions

Aditya Parameswaran, Anish Das Sarma, Hector Garcia-Molina, Neoklis Polyzotis, Jennifer Widom

Research output: Contribution to journalArticle


We consider the problem of human-assisted graph search: given a directed acyclic graph with some (unknown) target node(s), we consider the problem of finding the target node(s) by asking an omniscient human questions of the form "Is there a target node that is reachable from the current node?". This general problem has applications in many domains that can utilize human intelligence, including curation of hierarchies, debugging workflows, image segmentation and categorization, interactive search and filter synthesis. To our knowledge, this work provides the first formal algorithmic study of the optimization of human computation for this problem. We study various dimensions of the problem space, providing algorithms and complexity results. We also compare the performance of our algorithm against other algorithms, for the problem of webpage categorization on a real taxonomy. Our framework and algorithms can be used in the design of an optimizer for crowdsourcing platforms such as Mechanical Turk.

Original languageEnglish (US)
Pages (from-to)267-278
Number of pages12
JournalProceedings of the VLDB Endowment
Issue number5
StatePublished - Feb 2011

ASJC Scopus subject areas

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

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  • Cite this

    Parameswaran, A., Das Sarma, A., Garcia-Molina, H., Polyzotis, N., & Widom, J. (2011). Human-assisted graph search: It's okay to ask questions. Proceedings of the VLDB Endowment, 4(5), 267-278.