The complexity of independence-friendly fixpoint logic

Abstract. We study the complexity of model-checking for the fixpoint extension of Hintikka and Sandu’s independence-friendly logic. We show that this logic captures ExpTime; and by embedding PFP, we show that its combined complexity is ExpSpace-hard, and moreover the logic includes second order logic (on finite structures).

Clicks, elements and concurrency

Khoisan languages have always posed a challenge to formalphonology in the generative tradition, as their very large apparentinventories require an array of features used nowhere else. Irecently (2014) proposed a solution to this in terms of ‘concurrentphonemes’. In this article, I look at Khoisan from the pointof view of non-linear phonology, and investigate the applicationof the concurrent phoneme in this framework

Enriching OCL Using Observational Mu-Calculus

Abstract. The Object Constraint Language is a textual specificatio

An Effective Tableau System for the Linear Time µ-Calculus

We present a tableau system for the model checking problem of the linear time µ-calculus. It improves the system of Stirling and Walker by simplifying the success condition for a tableau. In our system success for a leaf is determined by the path leading to it, whereas Stirling and Walker's method requires the examination of a potentially infinite number of paths extending over the whole tableau

Fixpoint Alternation: Arithmetic, Transition Systems, and the Binary Tree

We provide an elementary proof of the fixpoint alternationhierarchy in arithmetic, which in turn allows us to simplify the proof of the modal mu-calculus alternation hierarchy. We further show that the alternation hierarchy on the binary tree is strict, resolving a problem of Niwinski

Observational mu calculus

We propose an extended modal mu-calculus to provide an `assembly language' for modal logics for real time, value-passing calculi, and other extended models of computation