Comparison of the two null models on a toy hypergraph. The hypergraph-graph abstraction follows the trans-primal procedure. Left: Traditional way of the null model generation by first abstracting the hypergraph and then rewiring. Right: New way of null model generation, maintaining the reaction size distribution, by first rewiring the hypergraph and then abstracting it. Note that the rewiring process does not necessarily preserve the overlapping reactants (e.g., reactant D in the toy hypergraph).