701 research outputs found
Thinking culturally about place
This paper explains the bases for an alternative approach to place branding and marketing, based on the disciplines of Cultural Mapping and Cultural Planning. After an introduction of key cultural mapping and planning concepts and issues, the paper discusses some innovative practical examples of culturally sensitive place branding and marketing from Sweden and the UK, and concludes by outlining some components of a possible future agenda for action
Quantifier-Free Interpolation of a Theory of Arrays
The use of interpolants in model checking is becoming an enabling technology
to allow fast and robust verification of hardware and software. The application
of encodings based on the theory of arrays, however, is limited by the
impossibility of deriving quantifier- free interpolants in general. In this
paper, we show that it is possible to obtain quantifier-free interpolants for a
Skolemized version of the extensional theory of arrays. We prove this in two
ways: (1) non-constructively, by using the model theoretic notion of
amalgamation, which is known to be equivalent to admit quantifier-free
interpolation for universal theories; and (2) constructively, by designing an
interpolating procedure, based on solving equations between array updates.
(Interestingly, rewriting techniques are used in the key steps of the solver
and its proof of correctness.) To the best of our knowledge, this is the first
successful attempt of computing quantifier- free interpolants for a variant of
the theory of arrays with extensionality
Fixed-point elimination in the intuitionistic propositional calculus
It is a consequence of existing literature that least and greatest
fixed-points of monotone polynomials on Heyting algebras-that is, the algebraic
models of the Intuitionistic Propositional Calculus-always exist, even when
these algebras are not complete as lattices. The reason is that these extremal
fixed-points are definable by formulas of the IPC. Consequently, the
-calculus based on intuitionistic logic is trivial, every -formula
being equivalent to a fixed-point free formula. We give in this paper an
axiomatization of least and greatest fixed-points of formulas, and an algorithm
to compute a fixed-point free formula equivalent to a given -formula. The
axiomatization of the greatest fixed-point is simple. The axiomatization of the
least fixed-point is more complex, in particular every monotone formula
converges to its least fixed-point by Kleene's iteration in a finite number of
steps, but there is no uniform upper bound on the number of iterations. We
extract, out of the algorithm, upper bounds for such n, depending on the size
of the formula. For some formulas, we show that these upper bounds are
polynomial and optimal
Macroeconomic Effects of Dividend Taxation with Investment Credit Limits
A dynamic general equilibrium model with an occasionally-binding investment borrowing limit reconciles competing views on the macroeconomic effects of dividend taxation. Specifically, permanent tax reforms are distortionary in the credit-constrained long-run equilibrium but are neutral otherwise. In the short- to medium-term, tax cuts produce muted, expansionary, or contractionary impacts depending on their scale, duration, and the firm's credit position. Interactions between dividend tax shocks and the financial constraint tightness generate state-contingent, non-linear, and asymmetrical macroeconomic dynamics. These findings help explain investment rate and asset price fluctuations observed following historical tax reforms. Finally, we explore the implications of dividend tax uncertainty
Dividend Taxation and Financial Business Cycles
We examine the interactions between different dividend tax systems and financial shocks in a dynamic stochastic general equilibrium (DSGE) model with an occasionally-binding investment credit limit. We show that dividend taxes largely determine the collateral value of assets, thereby occasionally distorting investment decisions and altering the propagation of financial shocks. Permanently lower dividend taxes dampen financially-driven business cycles in a state-contingent fashion. They also help explain substantial macroeconomic asymmetries following equally-sized expansionary and contractionary financial shocks
Molecular dynamics simulation of aqueous solutions of 26-unit segments of p(NIPAAm) and of p(NIPAAm) "doped" with amino acid based comonomers
We have performed 75-ns molecular dynamics (MD) simulations of aqueous solutions of a 26-unit NIPAAm
oligomer at two temperatures, 302 and 315 K, below and above the experimentally determined lower critical
solution temperature (LCST) of p(NIPAAm). We have been able to show that at 315 K the oligomer assumes
a compact form, while it keeps a more extended form at 302 K. A similar behavior has been demonstrated
for a similar NIPAAm oligomer, where two units had been substituted by methacryloyl-l-valine (MAVA)
comonomers, one of them being charged and one neutral. For another analogous oligomer, where the same
units had been substituted by methacryloyl-l-leucine (MALEU) comonomers, no transition from the extended
to the more compact conformation has been found within the same simulation time. Statistical analysis of the
trajectories indicates that this transition is related to the dynamics of the oligomer backbone, and to the formation
of intramolecular hydrogen bonds and water-bridges between distant units of the solute. In the MAVA case,
we have also evidenced an important role of the neutral MAVA comonomer in stabilizing the compact coiled
structure. In the MALEU case, the corresponding comonomer is not equally efficacious and, possibly, is
even hindering the readjustment of the oligomer backbone. Finally the self-diffusion coefficient of water
molecules surrounding the oligomers at the two temperatures for selected relevant times is observed to
characteristically depend on the distance from the solute molecules
Finitely generated free Heyting algebras via Birkhoff duality and coalgebra
Algebras axiomatized entirely by rank 1 axioms are algebras for a functor and
thus the free algebras can be obtained by a direct limit process. Dually, the
final coalgebras can be obtained by an inverse limit process. In order to
explore the limits of this method we look at Heyting algebras which have mixed
rank 0-1 axiomatizations. We will see that Heyting algebras are special in that
they are almost rank 1 axiomatized and can be handled by a slight variant of
the rank 1 coalgebraic methods
Counting Constraints in Flat Array Fragments
We identify a fragment of Presburger arithmetic enriched with free function symbols and cardinality constraints for interpreted sets, which is amenable to automated analysis. We establish decidability and complexity results for such a fragment and we implement our algorithms. The experiments run in discharging proof obligations coming from invariant checking and bounded model-checking benchmarks show the practical feasibility of our decision procedure
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