  We study the structure of the international trade hypergraph consisting of
triangular hyperedges representing the exporter-importer-product relationship.
Measuring the mean hyperdegree of the adjacent vertices, we first find its
behaviors different from those in the pairwise networks and explain the origin
by tracing the relation between the hyperdegree and the pairwise degree. To
interpret the observed hyperdegree correlation properties in the context of
trade strategies, we decompose the correlation into two components by
identifying one with the background correlation remnant even in the exponential
random hypergraphs preserving the given empirical hyperdegree sequence. The
other component characterizes the net correlation and reveals the bias of the
exporters of low hyperdegree towards the importers of high hyperdegree and the
products of low hyperdegree, which information is not readily accessible in the
pairwise networks. Our study demonstrates the power of the hypergraph approach
in the study of real-world complex systems and offers a theoretical framework.
