Abstract
Partial order multiway search(POMS) is a fundamental problem that finds applications in crowdsourcing, distributed file systems, software testing, and more. This problem involves an interaction between an algorithm 𝒜 and an oracle, conducted on a directed acyclic graph 𝒢 known to both parties. Initially, the oracle selects a vertextin 𝒢 called thetarget. Subsequently, 𝒜 must identify the target vertex by probing reachability. In eachprobe, 𝒜 selects a setQof vertices in 𝒢, the number of which is limited by a pre-agreed valuek. The oracle then reveals, for each vertexq∈Q, whetherqcan reach the target in 𝒢. The objective of 𝒜 is to minimize the number of probes. We propose an algorithm to solve POMS in\(O(\log _{1+k} n + \frac{d}{k} \log _{1+d} n)\)probes, wherenrepresents the number of vertices in 𝒢, andddenotes the largest out-degree of the vertices in 𝒢. The probing complexity is asymptotically optimal. Our study also explores two new POMS variants: The first one, namedtaciturn POMS, is similar to classical POMS but assumes a weaker oracle, and the second one, namedEM POMS, is a direct extension of classical POMS to theexternal memory(EM) model. For both variants, we introduce algorithms whose performance matches or nearly matches the corresponding theoretical lower bounds.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.