A logical Reconstruction of Leonard Bloomfield's Linguistic Theory

In this work we present a logical reconstruction of Leonard Bloom- field’s theory of structural linguistics. First, the central notions of this theory are analyzed and discussed. In the following section, a recon- struction with the so-called structuralist approach in the philosophy of science is presented. After defining the general framework of Bloom- field’s theory, questions of lawlikeness and theoretical terms will be discussed. In a further step, this work aims to contribute to the dis- cussion of theory change and scientific realism, applied to linguistic theory. After the reconstruction of further theories of linguistics, it can be studied whether certain inter theoretical relations hold. It aims to be a contribution to the discussion on the foundations of linguistics

The Complexity of Satisfiability for Sub-Boolean Fragments of ALC

The standard reasoning problem, concept satisfiability, in the basic description logic ALC is PSPACE-complete, and it is EXPTIME-complete in the presence of unrestricted axioms. Several fragments of ALC, notably logics in the FL, EL, and DL-Lite family, have an easier satisfiability problem; sometimes it is even tractable. All these fragments restrict the use of Boolean operators in one way or another. We look at systematic and more general restrictions of the Boolean operators and establish the complexity of the concept satisfiability problem in the presence of axioms. We separate tractable from intractable cases.Comment: 17 pages, accepted (in short version) to Description Logic Workshop 201

Costly Inflation Misperceptions

One of the consequences of the euro changeover in 2002 was that for a period of several years people considerably overestimated actual inflation. The goal of this paper is to study whether misperceptions of this kind may have real effects, that is, whether they induce people to alter their behaviour. We also discuss the question how far the euro changeover and the ensuing discussion about price stability contributed to the recession that followed the changeover. Looking at the German restaurant sector, we find that people’s misperceptions can have significant negative effects. The contraction this sector experienced in the months after the changeover was too pronounced to be explained by normal business cycle movements. We provide a discussion about the causes of these misperceptions and how to avoid them in future changeovers.euro changeover, perceived inflation

The Complexity of Reasoning for Fragments of Autoepistemic Logic

Autoepistemic logic extends propositional logic by the modal operator L. A formula that is preceded by an L is said to be "believed". The logic was introduced by Moore 1985 for modeling an ideally rational agent's behavior and reasoning about his own beliefs. In this paper we analyze all Boolean fragments of autoepistemic logic with respect to the computational complexity of the three most common decision problems expansion existence, brave reasoning and cautious reasoning. As a second contribution we classify the computational complexity of counting the number of stable expansions of a given knowledge base. To the best of our knowledge this is the first paper analyzing the counting problem for autoepistemic logic

Model Checking CTL is Almost Always Inherently Sequential

The model checking problem for CTL is known to be P-complete (Clarke, Emerson, and Sistla (1986), see Schnoebelen (2002)). We consider fragments of CTL obtained by restricting the use of temporal modalities or the use of negations—restrictions already studied for LTL by Sistla and Clarke (1985) and Markey (2004). For all these fragments, except for the trivial case without any temporal operator, we systematically prove model checking to be either inherently sequential (P-complete) or very efficiently parallelizable (LOGCFL-complete). For most fragments, however, model checking for CTL is already P-complete. Hence our results indicate that in most applications, approaching CTL model checking by parallelism will not result in the desired speed up. We also completely determine the complexity of the model checking problem for all fragments of the extensions ECTL, CTL +, and ECTL +