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

Aging as a consequence of misrepair -- A novel theory of aging

It is now increasingly realized that the underlying mechanisms which govern aging is a complex interplay of genetic regulation and damage accumulation. Aging as a result of accumulation of ‘faults’ on cellular and molecular levels, has been proposed in the damage (fault)-accumulation theory by Kirkwood 2006. However, this theory fails to explain some aging phenotypes such as fibrosis and premature aging, since terms such as ‘damage’ and ‘fault’ are not specified. Therefore we introduce here a specification of the underlying mechanism of aging and arrive at a novel theory: aging of the body is a result of the accumulation of Misrepair of tissue. It emphasizes: a) it is Misrepair, not the original damage, that accumulates and leads to aging; and b) aging can occur at different levels, however aging of the body takes place at least on the tissue level, but not necessarily on cellular/molecular level. The novel concept of Misrepair introduced here unifies the understanding of the roles of environmental damage, repair, gene regulation, and multicellular structure in the aging process. The Misrepair-accumulation theory introduced in the present paper gives explanations for the aging phenotypes, premature aging, and the difference of longevity in different species, and is consistent with the point of view of physical theory of complex systems

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 +

Pd nanoparticles confined in mesoporous N-doped carbon silica supports: a synergistic effect between catalyst and support

Palladium nanoparticles of similar size were deposited on different supports, layers of carbon materials (with and without nitrogen doping) on the surface of a MCF (mesocellular foam) silica. For the generation of the N-doped carbon coatings, three different N sources were used to also investigate a possible influence of the N-doped carbon precursor and thus the structure of the N-doped carbons on their performance as catalyst support. These catalysts were tested for the Suzuki coupling and hydrogenation reactions. For the Suzuki reaction, the carbon coatings showed to increase dramatically the stability of the MCF material. Furthermore, when N-doped carbon coatings were applied, strong improvement of the stability of the catalysts was observed due to an enhanced interaction between metal nanoparticles and the support, preventing metal particle growth. In hydrogenation reactions, the presence of the N-doped carbon coating on the silica support increases the adsorption of aromatic compounds causing an enhancement of the catalytic activity of Pd NPs when compared to the non-doped supports.TU Berlin, Open-Access-Mittel - 2020DFG, 390540038, EXC 2008: UniSysCa

Farm household decisions under various tax policies: Comparative static results and evidence from household data

The study is devoted to the comparative static analysis and econometric estimation of farm household decisions under both standard and agricultural taxes. Accounting for labor market constraints a non-separable model is constructed implying increasing per-unit costs of accessing labor markets. To control for tax-induced adjustments related to labor market imperfections we compare the results to those derived from a separable approach, assuming perfect labor markets. Theoretical results suggest that most tax-induced responses are ambivalent mainly caused by shadow prices effects. Further, tax-induced effects differ between the two model versions. In particular standard taxes may imply production adjustments in the case of non-separability. Thus, income and value-added taxes are no more necessarily superior to agricultural taxes. Econometric analysis using individual household data from Mid-West Poland indicates remarkable responses to market surplus and input taxes. In contrast, standard and land taxes imply only negligible production adjustments. Thus, they seem to be superior, at least in the Polish case. --