Two-colorable perfect matching problem is to decide whether a graph has coloring with two colors such that each node has exactly one neighbor the same color as itself. The problem was proven to be NP-complete by Schaefer. It remains NP-complete even for planar cubic graphs.

I am interested in a variant where we want to decide whether input graph has coloring with two colors such each node has exactly one neighbor colored differently from itself. I call this Red-Blue perfect matching problem. I don't know whether this is a known problem.

How hard is deciding the existence of Red-Blue perfect matching?

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    $\begingroup$ Another way of stating this problem would be to ask whether the given graph has a perfect matching which is also a cut. $\endgroup$ May 4, 2019 at 7:30

1 Answer 1


As Mikhail noted, the problem was called Perfect Matching Cut in literatures. It was proved to be NP-complete in the following paper (see Theorem 1 on page 5), with a reduction from monotone 1-in-3-SAT:

Pinar Heggernes, Jan Arne Telle. Partitioning Graphs Into Generalized Dominating Sets.


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