We prove a strong nonstructure theorem for a class of metric structures with an unstable formula. As a consequence, we show that weak categoricity (that is, categoricity up to isomorphisms and not isometries) implies several weak versions of stability. This is the first step in the direction of the investigation of weak categoricity of metric classes.

This paper employs a multivariate dynamic conditional correlation GARCH model, which is developed by Engle (2001, 2002), to detect the timing and nature of changes in the comovement between Iranian output and prices for the periods after Iran–Iraq war , known as imposed war . The results showed that there is a weak correlation between output and prices after imposed war and  varies periodically...

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We show that at the onset of a cyclic fold bifurcation, a birhythmic medium composed of glycolytic oscillators displays turbulent dynamics. By computing the largest Lyapunov exponent, the spatial correlation function, and the average transient lifetime, we classify it as weak turbulence of a transient nature. Virtual heterogeneities generating unstable fast oscillations account for the transien...

Starting from a logic which speciies how to make deductions from a set of sentences (a ``at theory'), a way to generalise this to a partially ordered bag of sentences (a `structured theory') is given. The partial order is used to resolve connicts. If occurs below then is accepted only insofar as it does not connict with. We start with a language L, a set of interpretations M and a satisfaction ...

The existence and dynamical role of particular unstable solutions (exact coherent structures) of the Navier-Stokes equation is revealed in laboratory studies of weak turbulence in a thin, electromagnetically driven fluid layer. We find that the dynamics exhibit clear signatures of numerous unstable equilibrium solutions, which are computed using a combination of flow measurements from the exper...

According to Olson’s concept of encompassing organizations, strong two-party, plurality oriented political systems should create more ‘responsible’ public policies than ‘weak’ multi-party governments based on proportional representation. An empirical measure of ‘encompassment’, termed popular cabinet support, is developed and tested in a multivariate controlled statistical analysis of 18 indust...

For small involutive and integral quantaloids Q it is shown that covariant presheaves on symmetric Q-categories are equivalent to certain subalgebras of a speci c monad on the category of symmetric Q-categories. This construction is related to a weakening of the subobject classi er axiom which does not require the classi cation of all subalgebras, but only guarantees that classi able subalgebra...