node_in_strong() assigns nodes' component membership based on edge direction.
In graph theory, components, sometimes called connected components, are induced subgraphs from partitioning the nodes into disjoint sets. All nodes that are members of the same partition as i are reachable from i.
For directed networks, strongly connected components consist of subgraphs where there are paths in each direction between member nodes. Weakly connected components consist of subgraphs where there is a path in either direction between member nodes.
Coreness captures the maximal subgraphs in which each vertex has at least degree k, where k is also the order of the subgraph. As described in igraph::coreness, a node's coreness is k if it belongs to the k-core but not to the (k+1)-core.