Just started using igraph a few days ago and really like it. I'm working with directed, valued data (migration between countries), and analysing coreness. When I use mode="all" there is very little change at all,but I notice very different trends using the coreness mode="out" and mode="in" values - could anyone give a common-sense/lay person's interpretation of what these measurements mean? Or possibly a good/link reference to follow up with? Thanks very much.