preventing cycles

[Wes Freeman]

What's the best way to prevent cycles in a graph? I'm building a graph that is usually more like a tree, but sometimes nodes point up to higher levels in the tree (direction matters). I want to make sure that when that happens, the higher level node is not a parent of the current node.

Say I have this graph: http://console.neo4j.org/r/en0t9x. I'm currently at node D1, and I successfully created a link to B3, but I would want to prevent links from D1 to B1 or A, for example. The only thing I have in my process is a list of node names I "want" to connect to, and that list might contain D1 or B1.

Thanks,

Wes

[Michael Hunger]

Wes,

you can use paths as predicates 

e.g.

start current= ..., target= ...

where NOT(current<-[:linked*]-target)

create current-[:linked]->target

HTH

Michael

[Wes Freeman]

Awesome, thanks. I'll give that a try.

Wes