In this paper, we introduce a variant of second-order propositional modal logic interpreted on general (or Henkin) frames, \(SOPML^{\mathcal {H}}\), and present a decidable fragment of this logic, \(SOPML^{\mathcal {H}}_{dec}\), that preserves important expressive capabilities of \(SOPML^{\mathcal {H}}\). \(SOPML^{\mathcal {H}}_{dec}\) is defined as a _modal loosely guarded fragment_ of \(SOPML^{\mathcal {H}}\). We demonstrate the expressive power of \(SOPML^{\mathcal {H}}_{dec}\) using examples in which modal operators obtain (a) the epistemic interpretation, (b) the dynamic interpretation. \(SOPML^{\mathcal {H}}_{dec}\) partially satisfies the principle of (...) non-Fregean logic: two different _atomic_ propositions with the same truth value can have different contents. In \(SOPML^{\mathcal {H}}_{dec}\), we also define _relating connectives_ and show that the _weak Boethius’ Thesis_ built using these connectives is a valid formula of \(SOPML^{\mathcal {H}}_{dec}\). (shrink)

This paper addresses the problem of ensuring that agents' plans are epistemically feasible in multiagent systems specifications. We propose some solutions within the Cognitive Agents Specification Language . We define a subjective execution construct Subj that causes the plan to be executed in terms of the agent's knowledge state, rather than in terms of the world state. The definition assumes that the agent does not do planning or lookahead, and chooses arbitrarily among the actions allowed by the plan. We also (...) define another deliberative execution operator Delib for smarter agents that do planning. We show how these notions can be used to express whether a process is epistemically feasible for its agent in several types of situations. More generally, the paper shows how a formalization of epistemic feasibility can be integrated with a transition-system semantics for an agent programming/specification language. (shrink)