Subsumption Algorithms for Three-Valued Geometric Resolution

In our implementation of geometric resolution, the most costly operation is subsumption testing (or matching): One has to decide for a three-valued, geometric formula, if this formula is false in a given interpretation. The formula contains only atoms with variables, equality, and existential quantifiers. The interpretation contains only atoms with constants. Because the atoms have no term structure, matching for geometric resolution is hard. We translate the matching problem into a generalized constraint satisfaction problem, and discuss several approaches for solving it efficiently, one direct algorithm and two translations to propositional SAT. After that, we study filtering techniques based on local consistency checking. Such filtering techniques can a priori refute a large percentage of generalized constraint satisfaction problems. Finally, we adapt the matching algorithms in such a way that they find solutions that use a minimal subset of the interpretation. The adaptation can be combined with every matching algorithm. The techniques presented in this paper may have applications in constraint solving independent of geometric resolution.Comment: This version was revised on 18.05.201

Deciding regular grammar logics with converse through first-order logic

We provide a simple translation of the satisfiability problem for regular grammar logics with converse into GF2, which is the intersection of the guarded fragment and the 2-variable fragment of first-order logic. This translation is theoretically interesting because it translates modal logics with certain frame conditions into first-order logic, without explicitly expressing the frame conditions. A consequence of the translation is that the general satisfiability problem for regular grammar logics with converse is in EXPTIME. This extends a previous result of the first author for grammar logics without converse. Using the same method, we show how some other modal logics can be naturally translated into GF2, including nominal tense logics and intuitionistic logic. In our view, the results in this paper show that the natural first-order fragment corresponding to regular grammar logics is simply GF2 without extra machinery such as fixed point-operators.Comment: 34 page

Vortex motion and Josephson effect in superconducting microbridges in (001) and (105) oriented YBaCuO thin films

Microbridges with dimensions smaller than the effective penetration depth have been prepared in epitaxially grown

A Recursive Inclusion Checker for Recursively Defined Subtypes

We present a tableaux procedure that checks logical relations between recursively defined subtypes of recursively defined types and apply this procedure to the problem of resolving ambiguous names in a programming language. This work is part of a project to design a new programming language suitable for efficient implementation of logic. Logical formulas are tree-like structures with many constructors having different arities and argument types. Algorithms that use these structures must perform case analysis on the constructors, and access subtrees whose type and existence depend on the constructor used. In many programming languages, case analysis is handled by matching, but we want to take a different approach, based on recursively defined subtypes. Instead of matching a tree against different constructors, we will classify it by using a set of disjoint subtypes. Subtypes are more general than structural forms based on constructors, we expect that they can be implemented more efficiently, and in addition can be used in static type checking. This makes it possible to use recursively defined subtypes as preconditions or postconditions of functions. We define the types and the subtypes (which we will call adjectives), define their semantics, and give a tableaux-based inclusion checker for adjectives. We show how to use this inclusion checker for resolving ambiguous field references in declarations of adjectives. The same procedure can be used for resolving ambiguous function calls

High-Tc bolometers with silicon-nitride spiderwebsuspension for far-infrared detection

High-Tc GdBa2Cu3O7-δ (GBCO) superconducting transition edge bolometers with operating temperatures near 90 K have been made with both closed silicon-nitride membranes and patterned silicon-nitride (SiN) spiderweb-like suspension structures. As a substrate silicon-on-nitride (SON) wafers are used which are made by fusion bonding of a silicon wafer to a silicon wafer with a silicon-nitride top layer. The resulting monocrystalline silicon top layer on the silicon-nitride membranes enables the epitaxial growth of GBCO. By patterning the silicon-nitride the thermal conductance G is reduced from about 20 to 3 μW/K. The noise of both types of bolometers is dominated by the intrinsic noise from phonon fluctuations in the thermal conductance G. The optical efficiency in the far infrared is about 75% due to a goldblack absorption layer. The noise equivalent power NEP for FIR detection is 1.8 pW/√Hz, and the detectivity D* is 5.4×1010 cm √Hz/W. Time constants are 0.1 and 0.6 s, for the closed membrane and the spiderweb like bolometers respectively. The effective time constant can be reduced with about a factor 3 by using voltage bias. Further reduction necessarily results in an increase of the NEP due to the 1/f noise of the superconductor

L'organisation de l'espace en région Centre

Les chorèmes et modèles constituent une méthode de représentation graphique nouvelle applicable à toute unité spatiale bien qu'il y ait des problèmes particuliers à chaque cas