Fundamental assumptions behind qualitative modelling are critically considered and some inherent problems in that modelling approach are outlined. The problems outlined are due to the assumption that a sufficient set of symbols representing the fundamental features of the physical world exists. That assumption causes serious problems when modelling continuous systems. An alternative for intelligent system building for cases not suitable for qualitative modelling is proposed. The proposed alternative combines neural networks and quantitative modelling.

Stationary spacetimes containing a black hole have several properties akin to those of atoms. For instance, such spacetimes have only three classical degrees of freedom, or observables, which may be taken to be the mass, the angular momentum, and the electric charge of the hole. There are several arguments supporting a proposal originally made by Bekenstein that quantization of these classical degrees of freedom gives an equal spacing for the horizon area spectrum of black holes. We review some of these (...) arguments and introduce a specific Hamiltonian quantum theory of black holes. Our Hamiltonian quantum theory gives, among other things, a discrete spectrum for the classical observables, and it produces an area spectrum which is closely related to Bekenstein's proposal. We also present a foamlike model of horizons of spacetime. In our model spacetime horizon consists of microscopic Schwarzschild black holes. Applying our Hamiltonian approach to this model we find that the entropy of any horizon is one quarter of its area. (shrink)

We study the computational complexity of the model checking problem for quantifier-free dependence logic ${(\mathcal{D})}$ formulas. We characterize three thresholds in the complexity: logarithmic space (LOGSPACE), non-deterministic logarithmic space (NL) and non-deterministic polynomial time (NP).

This study contributes to understanding stakeholder engagement strategies by examining competitive responses alongside sociopolitical implications after a major exogenous shock—the 1998 Master Settlement Agreement (MSA) between the “Big Four” U.S. tobacco firms and 46 state attorneys general. We compare the different stakeholder engagement strategies of the two remaining U.S. tobacco manufacturers, Philip Morris (PM) and R. J. Reynolds (RJR), between 1998 and 2017. Implications for stakeholder theory from a relatively rare natural experiment highlight the importance of simultaneously managing multiple stakeholders, (...) inclusive of domestic and international sociopolitical and value chain stakeholders over time, for sustained value creation. Although PM and RJR initially pursued heterogeneous strategies by re-configuring relationships with relevant stakeholders, each firm’s growth prospects for the first decade post-MSA were exacerbated by various stakeholders through withholding and selective engagement strategies. Implications for how multiple, simultaneous stakeholder relationships can serve as important resources for achieving or limiting sustained growth are discussed. (shrink)

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