On Mon, Mar 21, 2016 at 3:25 AM, Paolo Bolzoni <paolo.bolzoni.brown@gmail.com> wrote:

The text states the table summarizes which operations cause
descriptors and iterators to become invalid, said so what does
"OK" means? My feeling is that iterators never become invalid,
is that the case?

That's correct -- descriptors/iterators marked "OK" remain valid after the associated function is called (besides descriptors/iterators to the removed element itself, of course).

And what "EL=vecS && Directed=directedS" means? It means that
you are _fine_ only if you are working with a adjcency_list with
OutEdgeList as vecS and Directed=directedS or the opposite
(i.e., if you are using such adjcency_list then all iterators
become invalid)

It means the latter -- if you are using such an adjacency_list, then all descriptors/iterators become invalid. I believe the current implementation of adjacency_list uses vector indices as descriptors and pointers into the vector as iterators, and since the implementation guarantees that the vector is contiguous, removing vertex 5 in a 10-vertex graph will cause vertices to be re-numbered, invalidating old descriptors. If you want descriptors/iterators to remain valid as the graph is changed, it is therefore advisable to choose a datastructure such as a list which does not suffer this problem.

Cheers,

- Chris