Hypergraphs are a generalization of graphs, where the edges can connect any number of nodes (1 or more nodes). There can be directed and undirected edges in a hypergraph. In a directed edge, some of the edges are marked as the head, and the others are the tail. Hypergraphs have been used extensively in NLP for parsing or machine translation with grammars.
Search ACL Anthology for Hypergraphs.
Neural papers that use hypergraphs.