I have learned a net, and A->B should be B->A. Is this a bug ?

[Anders L Madsen]

No. During the learning process, a number of situations may arise, which forces a given link to obtain a fixed direction (e.g., to avoid cycles in the network). This can, occasionally, produce the above mentioned result. Using the NPC-algorithm minimizes the occurences of this, as the user is consulted in most cases. It is also possible, that the data actually indicates that the link should have the mentioned direction. Typically, this can happen if the amount of data is low (see "How much data do I need to learn a network ?").