Title
A Fixed-Parameter Perspective on #BIS.
Abstract
The problem of (approximately) counting the independent sets of a bipartite graph (#BIS) is the canonical approximate counting problem that is complete in the intermediate complexity class # RH Pi(1). It is believed that #BIS does not have an efficient approximation algorithm but also that it is not NP-hard. We study the robustness of the intermediate complexity of #BIS by considering variants of the problem parameterised by the size of the independent set. We map the complexity landscape for three problems, with respect to exact computation and approximation and with respect to conventional and parameterised complexity. The three problems are counting independent sets of a given size, counting independent sets with a given number of vertices in one vertex class and counting maximum independent sets amongst those with a given number of vertices in one vertex class. Among other things, we show that all of these problems are NP-hard to approximate within any polynomial ratio. (This is surprising because the corresponding problems without the size parameter are complete in # RH Pi(1), and hence are not believed to be NP-hard.) We also show that the first problem is # W[1]-hard to solve exactly but admits an FPTRAS, whereas the other two are W[1]-hard to approximate even within any polynomial ratio. Finally, we show that, when restricted to graphs of bounded degree, all three problems have efficient exact fixed-parameter algorithms.
Year
DOI
Venue
2017
10.1007/s00453-019-00606-4
ALGORITHMICA
Keywords
DocType
Volume
Approximate counting,Parameterised complexity,Independent sets
Conference
81.0
Issue
ISSN
Citations 
SP10
0178-4617
2
PageRank 
References 
Authors
0.41
10
5
Name
Order
Citations
PageRank
Radu Curticapean1708.75
Holger Dell222016.74
Fedor V. Fomin33139192.21
leslie ann goldberg41411125.20
John Lapinskas5134.25