eng
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
Leibniz International Proceedings in Informatics
1868-8969
2021-02-04
80:1
80:20
10.4230/LIPIcs.ITCS.2021.80
article
Erasure-Resilient Sublinear-Time Graph Algorithms
Levi, Amit
1
Pallavoor, Ramesh Krishnan S.
2
https://orcid.org/0000-0003-1060-7466
Raskhodnikova, Sofya
2
Varma, Nithin
3
https://orcid.org/0000-0002-1211-2566
David R. Cheriton School of Computer Science, University of Waterloo, Canada
Department of Computer Science, Boston University, MA, USA
Department of Computer Science, University of Haifa, Israel
We investigate sublinear-time algorithms that take partially erased graphs represented by adjacency lists as input. Our algorithms make degree and neighbor queries to the input graph and work with a specified fraction of adversarial erasures in adjacency entries. We focus on two computational tasks: testing if a graph is connected or ε-far from connected and estimating the average degree. For testing connectedness, we discover a threshold phenomenon: when the fraction of erasures is less than ε, this property can be tested efficiently (in time independent of the size of the graph); when the fraction of erasures is at least ε, then a number of queries linear in the size of the graph representation is required. Our erasure-resilient algorithm (for the special case with no erasures) is an improvement over the previously known algorithm for connectedness in the standard property testing model and has optimal dependence on the proximity parameter ε. For estimating the average degree, our results provide an "interpolation" between the query complexity for this computational task in the model with no erasures in two different settings: with only degree queries, investigated by Feige (SIAM J. Comput. `06), and with degree queries and neighbor queries, investigated by Goldreich and Ron (Random Struct. Algorithms `08) and Eden et al. (ICALP `17). We conclude with a discussion of our model and open questions raised by our work.
https://drops.dagstuhl.de/storage/00lipics/lipics-vol185-itcs2021/LIPIcs.ITCS.2021.80/LIPIcs.ITCS.2021.80.pdf
Graph property testing
Computing with incomplete information
Approximating graph parameters