6 research outputs found
Reasoning About the Transfer of Control
We present DCL-PC: a logic for reasoning about how the abilities of agents
and coalitions of agents are altered by transferring control from one agent to
another. The logical foundation of DCL-PC is CL-PC, a logic for reasoning about
cooperation in which the abilities of agents and coalitions of agents stem from
a distribution of atomic Boolean variables to individual agents -- the choices
available to a coalition correspond to assignments to the variables the
coalition controls. The basic modal constructs of DCL-PC are of the form
coalition C can cooperate to bring about phi. DCL-PC extends CL-PC with dynamic
logic modalities in which atomic programs are of the form agent i gives control
of variable p to agent j; as usual in dynamic logic, these atomic programs may
be combined using sequence, iteration, choice, and test operators to form
complex programs. By combining such dynamic transfer programs with cooperation
modalities, it becomes possible to reason about how the power of agents and
coalitions is affected by the transfer of control. We give two alternative
semantics for the logic: a direct semantics, in which we capture the
distributions of Boolean variables to agents; and a more conventional Kripke
semantics. We prove that these semantics are equivalent, and then present an
axiomatization for the logic. We investigate the computational complexity of
model checking and satisfiability for DCL-PC, and show that both problems are
PSPACE-complete (and hence no worse than the underlying logic CL-PC). Finally,
we investigate the characterisation of control in DCL-PC. We distinguish
between first-order control -- the ability of an agent or coalition to control
some state of affairs through the assignment of values to the variables under
the control of the agent or coalition -- and second-order control -- the
ability of an agent to exert control over the control that other agents have by
transferring variables to other agents. We give a logical characterisation of
second-order control
Refining and Delegating Strategic Ability in ATL
We propose extending Alternating-time Temporal Logic (ATL) by an operator <i
refines-to G> F to express that agent i can distribute its powers to a set of
sub-agents G in a way which satisfies ATL condition f on the strategic ability
of the coalitions they may form, possibly together with others agents. We prove
the decidability of model-checking of formulas whose subformulas with this
operator as the main connective have the form ...<i_m
refines-to G_m> f, with no further occurrences of this operator in f.Comment: In Proceedings SR 2014, arXiv:1404.041
Hierarchical agent supervision
Agent supervision is a form of control/customization where a supervisor restricts the behavior of an agent to enforce certain requirements, while leaving the agent as much autonomy as possible. To facilitate supervision, it is often of interest to consider hierarchical models where a high level abstracts over low-level behavior details. We study hierarchical agent supervision in the context of the situation calculus and the ConGolog agent programming language, where we have a rich first-order representation of the agent state. We define the constraints that ensure that the controllability of in-dividual actions at the high level in fact captures the controllability of their implementation at the low level. On the basis of this, we show that we can obtain the maximally permissive supervisor by first considering only the high-level model and obtaining a high- level supervisor and then refining its actions locally, thus greatly simplifying the supervisor synthesis task