[acadien]

Think of it as loops in 5 dimensions (x,y,z,a,b). I believe each node connects to 10 different neighboring nodes (2 in each of 5 dimensions), although I could be mistaken on that. You can actually tune which direction you prefer the nodes to communicate over by passing certain flags when you submit a job.

Also here's an image... which I admit is not terribly useful, but its what the national lab people put out. https://computing.llnl.gov/tutorials/bgq/images/5Dtorus.400p...

[darkmighty]

Oh so it's actually a 5D grid that wraps around. Confusingly that would make the standard torus a 2D torus, they're referring to the surface dimension instead of the euclidean space it can be embedded into.