On the reduction of the CSP dichotomy conjecture to digraphs

It is well known that the constraint satisfaction problem over general relational structures can be reduced in polynomial time to digraphs. We present a simple variant of such a reduction and use it to show that the algebraic dichotomy conjecture is equivalent to its restriction to digraphs and that the polynomial reduction can be made in logspace. We also show that our reduction preserves the bounded width property, i.e., solvability by local consistency methods. We discuss further algorithmic properties that are preserved and related open problems.Comment: 34 pages. Article is to appear in CP2013. This version includes two appendices with proofs of claims omitted from the main articl

Process orientation of the world heritage city management system

Purpose This article aims to explain how the world heritage city management system may be improved, and the structure of its processes enhanced by including relevant stakeholders to reach better results, i.e. outputs and outcomes. With this aim, process-based orientation is proposed as a new management approach. Design/methodology The article is divided into two parts. In the first part, theoretical background of the world heritage city management system is given, and process orientation of heritage city management explained. In the second part theoretical concepts were applied to the cases of the world heritage cities (sites) of Split (Croatia) and Venice (Italy). A brief description of the basic characteristics (elements, processes) and of the main problems related to the results (outputs and outcomes) is followed by the application of the Unified Modelling Language as the method. The process architecture of the new management meta-model is presented, processes designed and documented, and activities and responsibilities among stakeholders, both existing as well as potential, within the proposed hierarchical structure shared. Findings By proposing the process-oriented approach to the management of world heritage cities, the paper sets out to contribute to the growing body of knowledge related to cultural heritage management (especially world heritage cities). By applying knowledge from different theories into a process-based approach to the management of world heritage cities, it enables UNESCO's directives to be implemented into the actual managerial system of a World Heritage Site (WHS). We find it potentially useful not only to WHS managers, but also to scholars and other experts who have managerial responsibilities but limited knowledge in this area

Subclasses of Normal Helly Circular-Arc Graphs

A Helly circular-arc model M = (C,A) is a circle C together with a Helly family \A of arcs of C. If no arc is contained in any other, then M is a proper Helly circular-arc model, if every arc has the same length, then M is a unit Helly circular-arc model, and if there are no two arcs covering the circle, then M is a normal Helly circular-arc model. A Helly (resp. proper Helly, unit Helly, normal Helly) circular-arc graph is the intersection graph of the arcs of a Helly (resp. proper Helly, unit Helly, normal Helly) circular-arc model. In this article we study these subclasses of Helly circular-arc graphs. We show natural generalizations of several properties of (proper) interval graphs that hold for some of these Helly circular-arc subclasses. Next, we describe characterizations for the subclasses of Helly circular-arc graphs, including forbidden induced subgraphs characterizations. These characterizations lead to efficient algorithms for recognizing graphs within these classes. Finally, we show how do these classes of graphs relate with straight and round digraphs.Comment: 39 pages, 13 figures. A previous version of the paper (entitled Proper Helly Circular-Arc Graphs) appeared at WG'0

Dimensionamento amostral e determinação do tamanho ótimo de parcelas para avaliação de mudas de berinjela e jiló

O número de plantas avaliados em experimentos deve ser uma amostra representativa da população. Seus dados devem ser confiáveis de modo que permitam alta probabilidade de acerto em experimentos subsequentes. Soma-se a isto o fato da literatura especializada ainda não fornecer respostas sobre o tamanho ótimo de parcela e de amostra para a maioria das culturas agrícolas na fase de mudas. Assim, objetivou-se determinar o dimensionamento de parcelas e de amostra na avaliação de mudas de berinjela e jiló. Para isso, dois experimentos foram desenvolvidos no município de Colatina - ES, onde ambas as mudas das hortícolas foram produzidas em bandejas de poliestireno expandido contendo 128 células. O primeiro teve como objetivo determinar o tamanho de amostra necessário para a estimação da média de características de qualidade de mudas de berinjela e jiló, aplicados sobre um conjunto de características (número de folhas; área foliar total; massa de matéria fresca de parte aérea, raízes e total; e, índice de qualidade de Dickson). Foram calculadas medidas de tendência central e de variabilidade, e verificadas a normalidade dos dados amostrais e então calculado o tamanho de amostra por simulação bootstrap. O requerimento do dimensionamento amostral é diferente entre as diferentes características dentro das mudas de berinjela e também de jiló e, diferente também para uma mesma característica entre as duas espécies. O tamanho de amostra para avaliar mudas, para erro de estimação de 10% da média estimada, com grau de confiança de 95%, é de 32 e 26 mudas de berinjela e jiló, respectivamente. O segundo teve como objetivo a determinação do tamanho ótimo de parcela para experimentos envolvendo mudas das solanáceas berinjela e jiló, aplicados sobre um conjunto de características (altura de parte aérea; diâmetro do caule; número de folhas; área foliar total; massa de matéria seca de parte aérea; massa de matéria seca de raiz; massa de matéria seca total; e índice de qualidade de Dickson). Foram calculadas medidas de tendência central e de variabilidade dos dados amostrais e então calculado o tamanho ótimo da parcela usando o método da máxima curvatura modificado, com simulação bootstrap. O tamanho ótimo da parcela é diferente para as características avaliadas em mudas de berinjela e jiló. Considerando a avaliação de todas as caraterísticas de parte aérea e radicular, o tamanho ótimo de parcela é de 6 e 5 mudas, para berinjela e jiló, respectivamente

SYNTHESIS AND APPLICATION OF CROWN ETHERS

Mono- and bis-benzo-15-crown-5-ether derivatives have been synthesized and determined their potentiometric K+ selectivity factors. Of bis-crown ether urethanes highly selective Iigands were found some of which was used as active ingredient in potassium selective membrane electrode. Sugar based crown ethers, aza-crowns and cryptands were also prepared and applied as chiral catalyst in enantioselective reactions

Relating Structure and Power: Comonadic Semantics for Computational Resources

Combinatorial games are widely used in finite model theory, constraint satisfaction, modal logic and concurrency theory to characterize logical equivalences between structures. In particular, Ehrenfeucht-Fraisse games, pebble games, and bisimulation games play a central role. We show how each of these types of games can be described in terms of an indexed family of comonads on the category of relational structures and homomorphisms. The index k is a resource parameter which bounds the degree of access to the underlying structure. The coKleisli categories for these comonads can be used to give syntax-free characterizations of a wide range of important logical equivalences. Moreover, the coalgebras for these indexed comonads can be used to characterize key combinatorial parameters: tree-depth for the Ehrenfeucht-Fraisse comonad, tree-width for the pebbling comonad, and synchronization-tree depth for the modal unfolding comonad. These results pave the way for systematic connections between two major branches of the field of logic in computer science which hitherto have been almost disjoint: categorical semantics, and finite and algorithmic model theory.Comment: To appear in Proceedings of Computer Science Logic 201

Anharmonicity of a Gatemon Qubit with a Few-Mode Josephson Junction

Coherent operation of gate-voltage-controlled hybrid transmon qubits (gatemons) based on semiconductor nanowires was recently demonstrated. Here we experimentally investigate the anharmonicity in epitaxial InAs-Al Josephson junctions, a key parameter for their use as a qubit. Anharmonicity is found to be reduced by roughly a factor of two compared to conventional metallic junctions, and dependent on gate voltage. Experimental results are consistent with a theoretical model, indicating that Josephson coupling is mediated by a small number of highly transmitting modes in the semiconductor junction

Another look at weak feedback polynomials in the nonlinear combiner. 1115-1119. Paper

Abstract-Feedback polynomials with low degree multiples of low weight should be avoided in linear feedback shift registers when used in nonlinear combiners. We consider another class of weak feedback polynomials, namely the class when taps are located in small groups. This class was introduced in 2004 demonstrating that the resulting distinguishing attack can sometimes be better than the one using low weight multiples. In this paper we take another look at these polynomials and give further insight to the theory behind the attack complexity. Using the Walsh transform we show an easy way to determine the attack complexity given a polynomial. Further, we show that the size of the vectors should sometimes be larger than previously known. We also give a simple relation showing when the new attack will outperform the simple attack based on low weight multiples