(Disclaimer: I am not a mathematician)<p>A not well-defined set A contains itself:<p><pre><code> A <element_of> A
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How to name a not well-defined set's property of containing itself via a nesting structure in other sets?<p><pre><code> A <element_of> B <element_of> A
A <element_of> B <element_of> C <element_of> A
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In hypergraphs, hyperedges can link multiple vertices. Metagraphs extend hypergraphs in that hyperedges can link multiple other hyperedges, as well as vertices. I have been unable to find a universally accepted definition of the concept of metagraphs.<p><pre><code> [hypergraph] hyperedge E links vertices A, B, and C
[metagraph] hyperedge E links vertices A, B, and C; hyperedge F links vertices A and B with hyperedge E
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How to call a metagraph with self-containment cycles whereby a hyperedge E points to itself via another hyperedge F?<p><pre><code> [nested cyclic metagraph?] hyperedge E links hyperedge F with vertices B and C; hyperedge F links vertices A and B with hyperedge E
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A similar nesting parallel may be drawn with n-categories.<p>Finding literature on such data structures may become easier with a commonly accepted name, but the latter has eluded me for years. Should you have any ideas or pointers, please, put them down here.