The standard operation for FSM to compose knowledge sources is composition. You can compose different level graphs and differentiate them too. Awni's paper talk

The standard operation for FSM to compose knowledge sources is composition. You can compose different level graphs and differentiate them too. Awni's paper talks about that https://openreview.net/pdf?id=MpStQoD73Mj https://openreview.net/pdf?id=MpStQoD73Mj. The problem is that you need to differentiate graph structure, not just weights. This is a problem since the weights are inherently non-continuous.