Modeling with Rules

Rewriting Deontic Positions in Terms of Power

Let's imagine that we have a duty d for john to #pay another agent paul.

duty {
    holder: john
    counterparty: paul
    action: #pay
    violation: timeout
} as d

Now we have obtained a deontic view on the payment. However, this only models part of the problem. We could introduce a transformational rule that refines the context when a payment duty is introduced.

d -> {
    john.#pay => +power {
        holder: paul
        action: #declare_fulfillment { item: d }
        consequence: +d.fulfilled
    }
    timeout => +power {
        holder: paul
        action: #declare_violation { item: d }
        consequence: +d.violated
    }
}

Within this context, the agent john can perform the action #pay, which allows the counterparty paul to #declare_fulfillment of the original duty.

Moreover, we can provide further detail on the violation mechanism. In this case, we actively provide the counterparty with the power to #declare_violation.

This explicit model allows for better tracing of the activities performed by the agents and brings power at the forefront of the modeling strategy.

Rewriting Knowledge in Terms of Power

Transformational rules can be seen not only as epistemic duties of producing knowledge, but also as powers.

For instance, we could model the epistemic knowledge that a car constitutes a vehicle.

car -> vehicle

However, thanks to transformational rules being able to create contexts, we can further refine the implications of some piece of knowledge.

For example, when modeling a Vehicle Licensing Agency system, we might want to express duties and powers related to the existence of vehicles.

car -> {
    duty {
        holder: *
        action: +vehicle
    }
    power {
        holder: *
        action: #state { item: vehicle }
        consequence: +vehicle
    }
}

Here we express the epistemic duty to activate the vehicle state, but also the power for a someone to actively #state the existence of a vehicle.