It's not a 'cyclic data structure' though. It allows cycles in that every node has an ID and you can freely point to nodes to create cycles. For a cyclic graph

It's not a 'cyclic data structure' though. It allows cycles in that every node has an ID and you can freely point to nodes to create cycles. For a cyclic graph with true cycles see https://www.cs.utexas.edu/~wcook/Drafts/2012/graphs.pdf https://www.cs.utexas.edu/~wcook/Drafts/2012/graphs.pdf