A characterization of irreducible infeasible subsystems in flow networks

Infeasible network flow problems with supplies and demands can be characterized via violated cut-inequalities of the classical Gale-Hoffman theorem. Written as a linear program, irreducible infeasible subsystems (IISs) provide a different means of infeasibility characterization. In this article, we...

Full description

Bibliographic Details
Main Authors: Joormann, Imke, Pfetsch, Marc E., Orlin, James B
Other Authors: Sloan School of Management
Format: Article
Language:en_US
Published: Wiley Blackwell 2017
Online Access:http://hdl.handle.net/1721.1/111098
https://orcid.org/0000-0002-7488-094X
Description
Summary:Infeasible network flow problems with supplies and demands can be characterized via violated cut-inequalities of the classical Gale-Hoffman theorem. Written as a linear program, irreducible infeasible subsystems (IISs) provide a different means of infeasibility characterization. In this article, we answer a question left open in the literature by showing a one-to-one correspondence between IISs and Gale-Hoffman-inequalities in which one side of the cut has to be weakly connected. We also show that a single max-flow computation allows one to compute an IIS. Moreover, we prove that finding an IIS of minimal cardinality in this special case of flow networks is strongly NP-hard.