Network flows: theory, algorithms, and applications
Network flows: theory, algorithms, and applications
An orientation theorem with parity conditions
Discrete Applied Mathematics - Special issue on selected papers from First Japanese-Hungarian Symposium for Discrete Mathematics and its Applications
Unique Sink Orientations of Cubes
FOCS '01 Proceedings of the 42nd IEEE symposium on Foundations of Computer Science
Directed Network Design with Orientation Constraints
SIAM Journal on Discrete Mathematics
Computational Complexity: A Modern Approach
Computational Complexity: A Modern Approach
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It is known that every multigraph with an even number of edges has an even orientation (i.e., all indegrees are even). We study parity constrained graph orientations under additional constraints. We consider two types of constraints for a multigraph G=(V,E): (1) an exact conflict constraint is an edge set C⊆E and a vertex v∈V such that C should not equal the set of incoming edges at v; (2) a subset conflict constraint is an edge set C⊆E and a vertex v∈V such that C should not be a subset of incoming edges at v. We show that it is NP-complete to decide whether G has an even orientation with exact or subset conflicts, for all conflict sets of size two or higher. We present efficient algorithms for computing parity constrained orientations with disjoint exact or subset conflict pairs.