7 research outputs found
Reasoning about Knowledge and Strategies under Hierarchical Information
Two distinct semantics have been considered for knowledge in the context of
strategic reasoning, depending on whether players know each other's strategy or
not. The problem of distributed synthesis for epistemic temporal specifications
is known to be undecidable for the latter semantics, already on systems with
hierarchical information. However, for the other, uninformed semantics, the
problem is decidable on such systems. In this work we generalise this result by
introducing an epistemic extension of Strategy Logic with imperfect
information. The semantics of knowledge operators is uninformed, and captures
agents that can change observation power when they change strategies. We solve
the model-checking problem on a class of "hierarchical instances", which
provides a solution to a vast class of strategic problems with epistemic
temporal specifications on hierarchical systems, such as distributed synthesis
or rational synthesis
Model Checking an Epistemic mu-calculus with Synchronous and Perfect Recall Semantics
We identify a subproblem of the model-checking problem for the epistemic
\mu-calculus which is decidable. Formulas in the instances of this subproblem
allow free variables within the scope of epistemic modalities in a restricted
form that avoids embodying any form of common knowledge. Our subproblem
subsumes known decidable fragments of epistemic CTL/LTL, may express winning
strategies in two-player games with one player having imperfect information and
non-observable objectives, and, with a suitable encoding, decidable instances
of the model-checking problem for ATLiR.Comment: 10 pages, Poster presentation at TARK 2013 (arXiv:1310.6382)
http://www.tark.or
Changing Observations in Epistemic Temporal Logic
We study dynamic changes of agents' observational power in logics of
knowledge and time. We consider CTL*K, the extension of CTL* with knowledge
operators, and enrich it with a new operator that models a change in an agent's
way of observing the system. We extend the classic semantics of knowledge for
perfect-recall agents to account for changes of observation, and we show that
this new operator strictly increases the expressivity of CTL*K. We reduce the
model-checking problem for our logic to that for CTL*K, which is known to be
decidable. This provides a solution to the model-checking problem for our
logic, but its complexity is not optimal. Indeed we provide a direct decision
procedure with better complexity
Arrows for knowledge-based circuits
Knowledge-based programs (KBPs) are a formalism for directly relating agents' knowledge and behaviour in a way that has proven useful for specifying distributed systems. Here we present a scheme for compiling KBPs to executable automata in finite environments with a proof of correctness in Isabelle/HOL. We use Arrows, a functional programming abstraction, to structure a prototype domain-specific synchronous language embedded in Haskell. By adapting our compilation scheme to use symbolic representations we can apply it to several examples of reasonable size