2,564 research outputs found
A logic for n-dimensional hierarchical refinement
Hierarchical transition systems provide a popular mathematical structure to
represent state-based software applications in which different layers of
abstraction are represented by inter-related state machines. The decomposition
of high level states into inner sub-states, and of their transitions into inner
sub-transitions is common refinement procedure adopted in a number of
specification formalisms.
This paper introduces a hybrid modal logic for k-layered transition systems,
its first-order standard translation, a notion of bisimulation, and a modal
invariance result. Layered and hierarchical notions of refinement are also
discussed in this setting.Comment: In Proceedings Refine'15, arXiv:1606.0134
Refinement by interpretation in {\pi}-institutions
The paper discusses the role of interpretations, understood as multifunctions
that preserve and reflect logical consequence, as refinement witnesses in the
general setting of pi-institutions. This leads to a smooth generalization of
the refinement-by-interpretation approach, recently introduced by the authors
in more specific contexts. As a second, yet related contribution a basis is
provided to build up a refinement calculus of structured specifications in and
across arbitrary pi-institutions.Comment: In Proceedings Refine 2011, arXiv:1106.348
Impact of harvest residues, fertilisers and N-fixing plants on growth and nutritional status of young Eucalyptus globulus plantations under Mediterranean conditions
Growth and nutritional status of young plants
of Eucalyptus were assessed in a field trial, under different
scenarios of harvest residue management and nutrient
availability. Treatments were as follows: incorporation of
harvest residues into the soil by harrowing (I); I with N
fertiliser application (IF); I with leguminous, Lupinus
luteus L., seeding (IL); removal of harvest residues (R); R
with N fertiliser application (RF); R with leguminous
seeding (RL); distribution of harvest residues on the soil
surface (S); S with N fertiliser application (SF). Treatments
were replicated four times in four blocks with a fully
randomised design. Tree growth (height and diameter at
breast height) was measured and understory biomass
destructively recorded. Tree nutritional status was assessed
by foliar analysis (N, Ca, Mg, P, K and leaf area). Significant
differences in growth between I, R and S treatments
were only detected at early stage. Intercropping with
Lupinus decreased tree growth during the early phase, but
after 5 years growth was similar to that measured in the I
and R treatments. Application of fertiliser enhanced tree
growth especially when harvest residues were retained on
the soil surface. Combining incorporation of harvest residues
with fertiliser application (IF) was the best option to
increase tree growth, which was significantly greater than
in the R and S. Initially, leaf N was positively affected by
the leguminous (RL and IL), but, after the first fertiliser
application (1 year after planting), greater N was observed in the IF, RF and SF, the difference decreasing gradually
over the following year
Two-ballot versus plurality rule: an empirical investigation on the number of candidates
Duverger claimed more than 50 years ago that the number of candidates in elections should be a function of electoral rules. Both his “law” and “hypothesis” suggest the number of candidates vying for seats in elections to be tightly linked to characteristics of the electoral process such as its degree of proportionality and the presence of runoffs. Here we test the validity of Duverger’s claim using data from municipal elections in Brazil. Our study differs from others in the field in two important dimensions. First, by using municipal data we avoid the usual problems that plague statistical analysis using cross-country data. Secondly, we have a truly exogenous source of variation due to a change in electoral legislation introduced by the constitutional reform of 1988: simple plurality remained the rule only in municipalities with less than 200,000 voters, and a second-ballot became mandatory for the others above that threshold. This allows for a neat identification strategy using panel data. Our main finding is that elections with runoffs lure greater numbers of candidates in municipalities with sufficiently high levels of heterogeneity.Duverger's law, runoff, heterogeneity
Diagnóstico dos principais problemas no cultivo de hortaliças no Estado do Amazonas.
bitstream/CNPH-2010/36457/1/ct-82.pd
Understanding memorable enogastronomic experiences: A qualitative approach
The objectives of this chapter are to:
- Introduce those factors that make a memorable enogastronomic experience for tourists visiting a destination;
- Present qualitative findings that reveal that gastronomy and wines play a major role in the way that visitors experience a destination and indicate that some travellers would return to the same destination to savour its unique gastronomy.info:eu-repo/semantics/acceptedVersio
Optimal distribution of active piezoelectric elements for noise attenuation in sandwich panels
In this paper, a multiobjective optimization approach for obtaining the optimal distribution of surface-bonded piezoelectric sensors and actuators for noise attenuation in sandwich panels is presented. The noise attenuation is achieved by using negative velocity feedback control with co-located sensors and actuators. The control gains are also optimized in order to obtain the most efficient noise attenuation in a given frequency band. An in-house implementation of a viscoelastic soft core sandwich plate finite element, including surface-bonded piezoelectric sensors and actuators with active control capabilities, is used for obtaining the frequency response of the panels. The sound transmission capability of the panels is evaluated using the radiated sound power, along with the Rayleigh integral approach, which is suitable for lightly coupled structural/acoustic problems. The Direct MultiSearch (DMS) optimization algorithm is used to minimize the added weight due to the piezoelectric material, minimizing also the number of required controllers and maximizing the noise attenuation. The total length of the radiated sound power curve is shown to be an effective measure of noise attenuation in a given frequency band. Trade-off Pareto fronts and the obtained optimal configurations are presented and discussed.info:eu-repo/semantics/publishedVersio
Verification for Everyone? An Overview of Dynamic Logic
This note, reporting the homonym keynote presented in the International Symposium on Molecular Logic and Computational Synthetic Biology 2018, traces an informal roadmap on Dynamic Logic (DL) field, focusing on its versatility and resilience to be adjusted and adopted in a wide class of application domains and computational paradigms. The exposition argues the room for developments on tagging DL to the analysis of synthetic biologic domain.publishe
Models as arrows: the role of dialgebras
A large number of computational processes can suitably be described as a combination of construction, i.e. algebraic, and observation, i.e. coalgebraic, structures. This paper suggests dialgebras as a generic model in which such structures can be combined and proposes a small calculus of dialgebras including a wrapping combinator and se- quential composition. To take good care of invariants in software design, the paper also discusses how dialgebras can be typed by predicates and proves that invariants are preserved through composition. This lays the foundations for a full calculus of invariant proof-obligation discharge for dialgebraic models.Fundação para a Ciência e a Tecnologia (FCT
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