[igraph] simplify returns non-simple graph

[Jorge Gil]

Hi,

I've got an undirected graph that when I calculate closeness or 
betweenness centrality it crashes R without an error message or explanation.

I'm creating the graph using an edges list, and use that exact script 
with other lists and it works. So I guess there must be some problem 
with the graph for that particular set of edges.

Querying 'is.simple(g)' returns FALSE, so that could be the reason for 
the crash?
But after doing 'simplify(graph, remove.multiple = TRUE, remove.loops = 
TRUE)' I still get FALSE result from is.simple.
Are there other conditions that make a graph not simple?

Are there special restrictions for graphs to be used in closeness and 
betweenness centrality that I'm forgetting?

Thanks in advance,
Jorge

--
Jorge Gil
PhD Candidate

TU Delft / Faculty of Architecture
Department of Urbanism
Chair of Spatial Planning and Strategy

Julianalaan 134
2628 BL Delft
P.O. Box 5043
2600 GA Delft
The Netherlands

www.tudelft.nl