W e consider the estimation by simulation of probabilities of rare but potentially damaging events i n Markovian systems. The problem is that the rarity of the event mitigates against its frequent occurence in simulation. Here we show how a reverse-time model m a y be simulated in place of the fonuard-time system in order to provide significantly faster estimates of the rare probabilities. A n ...

For each p 2 there exists a model M of I 0 () which satisses the Count(p) principle. Furthermore, if p contains all prime factors of q there exist n; r 2 M and a bijective map f 2 dom(M) mapping f1; 2 A corollary is a complete classiication of the Count(q) versus Count(p) problem. Another corollary shows that the pigeonhole principle for injective maps does not follow from any of the Count(q) p...

The rare K + → π + ν ¯ ν decay is investigated in the context of type II two-Higgs-doublet model (2HDM). By using the existing experimental data of the branching ratio, restrictions on the free parameters of the model m H , and tanβ are obtained: 0.7 ≤ tanβ ≤ 0.8, and 500GeV ≤ m H ≤ 700GeV .

We prove that if V ⊆ V[h] is a generic extension by Prikry forcing then every transitive intermediate model M of ZFC , where V $ M ⊆ V[h] , is again a Prikry generic extension of V . Moreover the family of intermediate models is parametrised by P(ω)/finite. The result is proved by studying V-constructibility degrees of sets in V[h] using parameters in V .

We show that an infinite number of non-unitary minimal models may describe two dimensional turbulent magnetohydrodynamics (MHD), both in the presence and absence of the Alf'ven effect. We argue that the existence of a critical dynamical index results in the Alf'ven effect or equivelently the equipartition of energy. We show that there are an infinite number of conserved quantities in 2D − M HD ...

Assume G is a group definable in a model M of a stable theory T . We prove that the semigroup SG(M) of complete G-types over M is an inverse limit of some semigroups type-definable in M eq. We prove that the maximal subgroups of SG(M) are inverse limits of some definable quotients of subgroups of G. We consider the powers of types in the semigroup SG(M) and prove that in a way every type in SG(...

In Bue93b] we proved Vaught's conjecture for all superstable theories of nite rank; that is, such a theory has countably many or continuum many countable models. While this proof does settle Vaught's conjecture for unidimensional theories a sharper result can be obtained for these theories and in places the proof can be simpliied. Let T be a properly unidimensional theory with < 2 @ 0 many coun...

In 2004 Csima, Hirschfeldt, Knight, and Soare [1] showed that a set A ≤T 0′ is nonlow2 if and only if A is prime bounding, i.e. for every complete atomic decidable theory T , there is a prime model M computable in A. The authors presented nine seemingly unrelated predicates of a set A, and showed that they are equivalent for ∆2 sets. Some of these predicates, such as prime bounding, and others ...