berge_acyclic (622B)
1 # Berge acyclic 2 3 A [hypergraph] is *Berge acyclic* if its [incidence_graph] is [graph_acyclic] 4 - In particular, whenever there are two [hyperedges] sharing more than one element, then the hypergraph is not Berge-acyclic 5 6 Can also be defined for [database_instances] and [CQs], but then the criterion is on the [incidence_multigraph] 7 - So whenever some element occurs twice in a [fact] or in an [atom] then the [database_instance] or [CQ] is not Berge acyclic 8 9 If a hypergraph is Berge acyclic then any [subhypergraph] also is 10 11 Up: [degree_of_acyclicity] 12 13 Aliases: Berge acyclicity, incidence acyclic, incidence acyclicity