Gradual Certified Programming in Coq

Expressive static typing disciplines are a powerful way to achieve high-quality software. However, the adoption cost of such techniques should not be under-estimated. Just like gradual typing allows for a smooth transition from dynamically-typed to statically-typed programs, it seems desirable to support a gradual path to certified programming. We explore gradual certified programming in Coq, providing the possibility to postpone the proofs of selected properties, and to check "at runtime" whether the properties actually hold. Casts can be integrated with the implicit coercion mechanism of Coq to support implicit cast insertion a la gradual typing. Additionally, when extracting Coq functions to mainstream languages, our encoding of casts supports lifting assumed properties into runtime checks. Much to our surprise, it is not necessary to extend Coq in any way to support gradual certified programming. A simple mix of type classes and axioms makes it possible to bring gradual certified programming to Coq in a straightforward manner.Comment: DLS'15 final version, Proceedings of the ACM Dynamic Languages Symposium (DLS 2015

Theoretical Analysis of Acceptance Rates in Multigrid Monte Carlo

We analyze the kinematics of multigrid Monte Carlo algorithms by investigating acceptance rates for nonlocal Metropolis updates. With the help of a simple criterion we can decide whether or not a multigrid algorithm will have a chance to overcome critial slowing down for a given model. Our method is introduced in the context of spin models. A multigrid Monte Carlo procedure for nonabelian lattice gauge theory is described, and its kinematics is analyzed in detail.Comment: 7 pages, no figures, (talk at LATTICE 92 in Amsterdam

The Length of an SLE - Monte Carlo Studies

The scaling limits of a variety of critical two-dimensional lattice models are equal to the Schramm-Loewner evolution (SLE) for a suitable value of the parameter kappa. These lattice models have a natural parametrization of their random curves given by the length of the curve. This parametrization (with suitable scaling) should provide a natural parametrization for the curves in the scaling limit. We conjecture that this parametrization is also given by a type of fractal variation along the curve, and present Monte Carlo simulations to support this conjecture. Then we show by simulations that if this fractal variation is used to parametrize the SLE, then the parametrized curves have the same distribution as the curves in the scaling limit of the lattice models with their natural parametrization.Comment: 18 pages, 10 figures. Version 2 replaced the use of "nu" for the "growth exponent" by 1/d_H, where d_H is the Hausdorff dimension. Various minor errors were also correcte

Vortex Dynamics in Classical Non--Abelian Spin Models

We discuss the abelian vortex dynamics in the abelian projection approach to non-abelian spin models. We show numerically that in the three-dimensional SU(2) spin model in the Maximal Abelian projection the abelian off-diagonal vortices are not responsible for the phase transition contrary to the diagonal vortices. A generalization of the abelian projection approach to SU(N) spin models is briefly discussed.Comment: 7 pages, LaTeX, 1 figure, uses epsf.sty; Introduction is extended and a few references are added; to be published in JETP Let

Kinetic Analysis of the Hydrocarbon Total Oxidation Using Individually Measured Adsorption Isotherms

Dedicated to Prof. Dr.-Ing. Andreas Seidel-Morgenstern on the occasion of his 60th birthda

THE EFFECT OF INSPIRED OXYGEN CONCENTRATION ON INTRAPULMONARY RIGHT-TO-LEFT SHUNT DURING POSTOPERATIVE MECHANICAL VENTILATION

A consecutive series of patients undergoing cardiac surgery for valve replacement was divided into two groups. The first underwent postoperative artificial ventilation using the oxygen-driven Bird ventilator. The inspiratory oxygen concentration was 83%. In the second group a Bird ventilator was also used but with an oxygen concentration of 40%. In the first group the intrapulmonary right-to-left shunt rose to an average of 17% during the first two postoperative daysand in the second group to an average of 9%. The study supports the view that the inspiratory oxygen concentration should only be kept high enough to achieve a normal oxygen saturation of arterial bloo