The Dynamic Complexity of Acyclic Hypergraph Homomorphisms

07/13/2021

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by   Nils Vortmeier, et al.

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Finding a homomorphism from some hypergraph 𝒬 (or some relational structure) to another hypergraph 𝒟 is a fundamental problem in computer science. We show that an answer to this problem can be maintained under single-edge changes of 𝒬, as long as it stays acyclic, in the DynFO framework of Patnaik and Immerman that uses updates expressed in first-order logic. If additionally also changes of 𝒟 are allowed, we show that it is unlikely that existence of homomorphisms can be maintained in DynFO.