Richer Interface Automata with Optimistic and Pessimistic Compatibility

Modal transition systems are a popular semantic underpinning of interface theories, such as Nyman et al.’s IOMTS and Bauer et al.’s MIO, which facilitate component-based reasoning of concurrent systems. Our interface theory MIA repaired a compositional flaw of IOMTS-refinement and introduced a conjunction operator. In this paper, we first modify MIA to properly deal with internal computations including internal must-transitions, which were largely ignored already in IOMTS. We then study a MIA variant that adopts MIO’s pessimistic – rather than IOMTS’ optimistic – view on component compatibility and define, for the first time in a pessimistic, non-deterministic setting, conjunction and disjunction on interfaces. For the pessimistic MIA variant we also provide a mechanism for extending alphabets when refining interfaces, which is a desired feature in practice. We illustrate our advancements via a small example

Hausmannskost für das liebe Volk. Antirevolutionäre Publizistik und fideistisches Weltbild in Adolph Kolpings "Katholischen Volkskalendern" 1850 bis 1853

Über den im Jahre 1865 verstorbenen Organisator der katholischen Gesellenvereine Adolph Kolping ist im Verlaufe von etwa 140 Jahren sehr vieles geschrieben worden, zumeist über den "Gesellenvater" und seine Pädagogik, vereinzelt auch über den "Schriftsteller" oder "Volksbildner". Nur ganz wenige dieser Veröffentlichungen können als historisch- kritisch eingestuft werden. (...) EnglishFranz Lüttgen: "Hausmannskost für das liebe Volk" (Husbandman's fare for the beloved people). Anti-revolutionary journalism and the fideistic view of the world in Adolf Kolping's "Katholischen Volkskalendern" (Catholic People's Calendar) from 1850 to 1853From 1850, Adolf Kolping (1813·1865). the organizer of the Catholic Joumeymen's Guild, published an annual "Peoples Calendar". As an acute observer of the revolution who tried to understand its failure from a christian point of view, the "Kalendermann" Kolping demonstrated a closeness in time to the events of 1848/1849 in his calendars for the years 1850 and 1851. He was not ashamed, while doing this, to newly define termssuch as "Democracy" and "Freedom" to suit his own purposes and fit into his concept. His foreward to the Katholischen Volkskalen · der 1852 is looked into from the point ofview of it as a popularisation of a fideistic or traditionalist view of the world in which the fundamental equality of all humans and the autonomy of the earthly reality were still unknown. The social consequences of this view of the world as they come to fruition in the popular tales and narratives in the Katholischen Volks· kaiender 1852 und 1853 show how Kolping fed Hausmannskost (Husbandman's fare) to his beloved people and not Hausfrauenkost (housewife's fare).

Efficient recovery of non-periodic multivariate functions from few scattered samples

It has been observed by several authors that well-known periodization strategies like tent or Chebychev transforms lead to remarkable results for the recovery of multivariate functions from few samples. So far, theoretical guarantees are missing. The goal of this paper is twofold. On the one hand, we give such guarantees and briefly describe the difficulties of the involved proof. On the other hand, we combine these periodization strategies with recent novel constructive methods for the efficient subsampling of finite frames in $\mathbb{C}$. As a result we are able to reconstruct non-periodic multivariate functions from very few samples. The used sampling nodes are the result of a two-step procedure. Firstly, a random draw with respect to the Chebychev measure provides an initial node set. A further sparsification technique selects a significantly smaller subset of these nodes with equal approximation properties. This set of sampling nodes scales linearly in the dimension of the subspace on which we project and works universally for the whole class of functions. The method is based on principles developed by Batson, Spielman, and Srivastava and can be numerically implemented. Samples on these nodes are then used in a (plain) least-squares sampling recovery step on a suitable hyperbolic cross subspace of functions resulting in a near-optimal behavior of the sampling error. Numerical experiments indicate the applicability of our results.Comment: 6 pages, 5 figures Published in the SampTA 2023 conference proceedin

Graphical representation of covariant-contravariant modal formulae

Covariant-contravariant simulation is a combination of standard (covariant) simulation, its contravariant counterpart and bisimulation. We have previously studied its logical characterization by means of the covariant-contravariant modal logic. Moreover, we have investigated the relationships between this model and that of modal transition systems, where two kinds of transitions (the so-called may and must transitions) were combined in order to obtain a simple framework to express a notion of refinement over state-transition models. In a classic paper, Boudol and Larsen established a precise connection between the graphical approach, by means of modal transition systems, and the logical approach, based on Hennessy-Milner logic without negation, to system specification. They obtained a (graphical) representation theorem proving that a formula can be represented by a term if, and only if, it is consistent and prime. We show in this paper that the formulae from the covariant-contravariant modal logic that admit a "graphical" representation by means of processes, modulo the covariant-contravariant simulation preorder, are also the consistent and prime ones. In order to obtain the desired graphical representation result, we first restrict ourselves to the case of covariant-contravariant systems without bivariant actions. Bivariant actions can be incorporated later by means of an encoding that splits each bivariant action into its covariant and its contravariant parts.Comment: In Proceedings EXPRESS 2011, arXiv:1108.407

Modal Interface Automata

De Alfaro and Henzinger's Interface Automata (IA) and Nyman et al.'s recent combination IOMTS of IA and Larsen's Modal Transition Systems (MTS) are established frameworks for specifying interfaces of system components. However, neither IA nor IOMTS consider conjunction that is needed in practice when a component shall satisfy multiple interfaces, while Larsen's MTS-conjunction is not closed and Bene\v{s} et al.'s conjunction on disjunctive MTS does not treat internal transitions. In addition, IOMTS-parallel composition exhibits a compositionality defect. This article defines conjunction (and also disjunction) on IA and disjunctive MTS and proves the operators to be 'correct', i.e., the greatest lower bounds (least upper bounds) wrt. IA- and resp. MTS-refinement. As its main contribution, a novel interface theory called Modal Interface Automata (MIA) is introduced: MIA is a rich subset of IOMTS featuring explicit output-must-transitions while input-transitions are always allowed implicitly, is equipped with compositional parallel, conjunction and disjunction operators, and allows a simpler embedding of IA than Nyman's. Thus, it fixes the shortcomings of related work, without restricting designers to deterministic interfaces as Raclet et al.'s modal interface theory does.Comment: 28 page

A Generalised Theory of Interface Automata, Component Compatibility and Error

Interface theories allow systems designers to reason about the composability and compatibility of concurrent system components. Such theories often extend both de Alfaro and Henzinger’s Interface Automata and Larsen’s Modal Transition Systems, which leads, however, to several issues that are undesirable in practice: an unintuitive treatment of specified unwanted behaviour, a binary compatibility concept that does not scale to multi-component assemblies, and compatibility guarantees that are insufficient for software product lines. In this paper we show that communication mismatches are central to all these problems and, thus, the ability to represent such errors semantically is an important feature of an interface theory. Accordingly, we present the error-aware interface theory EMIA, where the above shortcomings are remedied by introducing explicit fatal error states. In addition, we prove via a Galois insertion that EMIA is a conservative generalisation of the established MIA (Modal Interface Automata) theory

Robustness of a bisimulation-type faster-than preorder

TACS is an extension of CCS where upper time bounds for delays can be specified. Luettgen and Vogler defined three variants of bismulation-type faster-than relations and showed that they all three lead to the same preorder, demonstrating the robustness of their approach. In the present paper, the operational semantics of TACS is extended; it is shown that two of the variants still give the same preorder as before, underlining robustness. An explanation is given why this result fails for the third variant. It is also shown that another variant, which mixes old and new operational semantics, can lead to smaller relations that prove the same preorder.Comment: Express Worksho

Siddiqui, Negative refraction and focusing in hyperbolic transmission-line periodic grids

between an interface and the channel axes (cf. Ref. 3). This feature is counterintuitive to the conventional optical laws but it is totally consistent with the analysis based on the isofrequencies' for the channeled waves on anisotropic lattices discussed earlier. In the conventional isotropic periodic structures, a unit cell is representative of the respective finite arrangement when the edge cells are terminated into the matched loads. However, the feature of L-C mesh to funnel power from a point source into the narrow beam leads to the question whether load impedances of the edge cells nonadjacent to the beam axis affect the channel formation and properties of the propagating waves. To explore this effect, the load impedances outside the vicinities of the source and the channel output cells were varied. A comprehensive analysis of finite BM simulated in ADS has shown that only the first three edge nodes at the channel axis contribute to the beam formation. These observations led us to the conclusion that the channels arising on the anisotropic L-C mesh are well confined and guide waves along their axes as predicted by isofrequencies. To further elucidate the mechanism of wave channeling, the lattice portions were progressively removed to retain the mesh only around the channel axis. These alterations of the mesh arrangement incurred no visible changes of the beam shape and intensity on the truncated grids. Thus, the simulation results have proved that the propagation channel formed on the L-C mesh is truly confined to a few cells at the channel axis. This property of the L-C mesh suggests that a number of independent channels with their own impedances and axis orientations could be formed on the grid. Since the channel directions vary with frequency and the unit cell parameters, the L-C mesh can act as a spatial frequency discriminator CONCLUSIONS It has been shown that 2D periodic meshes composed of L-C circuits collimate waves from a point source into beams. The beam directions are prescribed by the lattice symmetry and the admittance ratio (Y 2 /Y 1 ) Ͻ 0. The basic properties of the channeled waves, determined by the isofrequencies, are invariant to the physical arrangements of the unit cells as long as the ratio (Y 2 /Y 1 ) remains constant. Effect of the unit cell structure on the channeled wave propagation has been explored for the unit cell configurations composed of double series (SSM), double parallel (PPM), and mixed parallel-series (PSM) L-C circuits. Analysis of these meshes has shown that the type (forward or backward) of channeled wave can be altered in the designed frequency band by varying only capacitance in the mesh arms. These findings are of particular significance for implementation of tunable meshes used in beam steering and phase compensation applications. Analysis of the channeled wave scattering at interfaces of dual L-C meshes showed that, in general, the "refracted" beams propagate only along the channel axes whose directions depend on the lattice parameters but not the angle of incidence onto interface. HIGH DIRECTIVITY IN LOW-PERMITTIVITY METAMATERIAL SLABS: RAY-OPTIC VS. LEAKY-WAVE MODEL

On the Unification of Process Semantics: Logical Semantics

We continue with the task of obtaining a unifying view of process semantics by considering in this case the logical characterization of the semantics. We start by considering the classic linear time-branching time spectrum developed by R.J. van Glabbeek. He provided a logical characterization of most of the semantics in his spectrum but, without following a unique pattern. In this paper, we present a uniform logical characterization of all the semantics in the enlarged spectrum. The common structure of the formulas that constitute all the corresponding logics gives us a much clearer picture of the spectrum, clarifying the relations between the different semantics, and allows us to develop generic proofs of some general properties of the semantics.Comment: In Proceedings SOS 2011, arXiv:1108.279