Decision Problems for Partial Specifications: Empirical and Worst-Case Complexities

Partial specifications allow approximate models of systems such as Kripke structures, or labeled transition systems to be created. Using the abstraction possible with these models, an avoidance of the state-space explosion problem is possible, whilst still retaining a structure that can have properties checked over it. A single partial specification abstracts a set of systems, whether Kripke, labeled transition systems, or systems with both atomic propositions and named transitions. This thesis deals in part with problems arising from a desire to efficiently evaluate sentences of the modal μ-calculus over a partial specification. Partial specifications also allow a single system to be modeled by a number of partial specifications, which abstract away different parts of the system. Alternatively, a number of partial specifications may represent different requirements on a system. The thesis also addresses the question of whether a set of partial specifications is consistent, that is to say, whether a single system exists that is abstracted by each member of the set. The effect of nominals, special atomic propositions true on only one state in a system, is also considered on the problem of the consistency of many partial specifications. The thesis also addresses the question of whether the systems a partial specification abstracts are all abstracted by a second partial specification, the problem of inclusion. The thesis demonstrates how commonly used “specification patterns” – useful properties specified in the modal μ-calculus, can be efficiently evaluated over partial specifications, and gives upper and lower complexity bounds on the problems related to sets of partial specifications

Refinement for Transition Systems with Responses

Motivated by the response pattern for property specifications and applications within flexible workflow management systems, we report upon an initial study of modal and mixed transition systems in which the must transitions are interpreted as must eventually, and in which implementations can contain may behaviors that are resolved at run-time. We propose Transition Systems with Responses (TSRs) as a suitable model for this study. We prove that TSRs correspond to a restricted class of mixed transition systems, which we refer to as the action-deterministic mixed transition systems. We show that TSRs allow for a natural definition of deadlocked and accepting states. We then transfer the standard definition of refinement for mixed transition systems to TSRs and prove that refinement does not preserve deadlock freedom. This leads to the proposal of safe refinements, which are those that preserve deadlock freedom. We exemplify the use of TSRs and (safe) refinements on a small medication workflow.Comment: In Proceedings FIT 2012, arXiv:1207.348

Literature in the audiovisual culture

The article shows that the biggest beneficiary of possibilities opened by infrastructure of information society is not contemporary literary avant-garde (hypertexts, electronic literature etc.) but popular literature ingrained in the very centre of social communication. Authors like Dehnel and Witkowski through their media activity, writing features in newspapers, blogging, using Facebook, organizing events in public space etc. blur the line between book and media environment and create interactive, transmedia literary space. Literature goes beyond books and libraries, like previously visual arts left traditional space of museum. Texts go out of books, enter a public space, meet people, connect with other media, setting up literary database scattered throughout the culture, which can be used in a different ways

An investigation of a frequency diverse array

This thesis presents a novel concept for focusing an antenna beam pattern as a function of range, time, and angle. In conventional phased arrays, beam steering is achieved by applying a linear phase progression across the aperture. This thesis shows that by applying an additional linear frequency shift across the elements, a new term is generated which results in a scan angle that varies with range in the far-field. Moreover, the antenna pattern is shown to scan in range and angle as a function of time. These properties result in more flexible beam scan options for phased array antennas than traditional phase shifter implementations. The thesis subsequently goes on to investigate this phenomenon via full scale experimentation, and explores a number of aspects of applying frequency diversity spatially across array antennas. This new form of frequency diverse array may have applications to multipath mitigation, where a radio signal takes two or more routes between the transmitter and receiver due to scattering from natural and man-made objects. Since the interfering signals arrive from more than one direction, the range-dependent and auto-scanning properties of the frequency diverse array beam may be useful to isolate and suppress the interference. The frequency diverse array may also have applications to wideband array steering, in lieu of true time delay solutions which are often used to compensate for linear phase progression with frequency across an array, and to sonar, where the speed of propagation results in large percentage bandwidth, creating similar wideband array effects. The frequency diverse array is also a stepping stone to more sophisticated joint antenna and waveform design for the creation of new radar modes, such as simultaneous multi-mode operation, for example, enabling joint synthetic aperture radar and ground moving target indication

On the complexity of semantic self-minimization

Partial Kripke structures model only parts of a state space and so enable aggressive abstraction of systems prior to verifying them with respect to a formula of temporal logic. This partiality of models means that verifications may reply with true (all refinements satisfy the formula under check), false (no refinement satisfies the formula under check) or dont know. Generalized model checking is the most precise verification for such models (all dont know answers imply that some refinements satisfy the formula, some dont), but computationally expensive. A compositional model-checking algorithm for partial Kripke structures is efficient, sound (all answers true and false are truthful), but may lose precision by answering dont know instead of a factual true or false. Recent work has shown that such a loss of precision does not occur for this compositional algorithm for most practically relevant patterns of temporal logic formulas. Formulas that never lose precision in this manner are called semantically self-minimizing. In this paper we provide a systematic study of the complexity of deciding whether a formula of propositional logic, propositional modal logic or the propositional modal mu-calculus is semantically self-minimizing. © 2009 Elsevier B.V. All rights reserved

Efficient Patterns for Model Checking Partial State Spaces in CTL & LTL

Compositional model checks of partial Kripke structures are efficient but incomplete as they may fail to recognize that all implementations satisfy the checked property. But if a property holds for such checks, it will hold in all implementations. Such checks are therefore under-approximations. In this paper we determine for which popular specification patterns, documented at a communityled pattern repository, this under-approximation is precise in that the converse relationship holds as well for all model checks. We find that many such patterns are indeed precise. Those that arent lose precision because of a sole propositional atom in mixed polarity. Hence we can compute, with linear blowup only, a semantic minimization in the same temporal logic whose efficient check renders the precise result for the original imprecise pattern. Thus precision can be secured for all patterns at low cost. © 2006 Elsevier B.V. All rights reserved

АНАЛІЗ НАПРЯМКІВ РОЗВИТКУ ОСВІТИ В УКРАЇНІ

The paper provides the analysis of the main form of development in Ukrainian education during the last one hundred years. Special attention is given to the quantitative indices of educational establishments of different levels and to the dynamics of student’s population growth. It studies the schoolteachers and university teachers stuff composition as well as the problems of pupils and students composition

Can we increase the intensity of pro-active balance exercises?

Balance training has been shown to be effective in preventing or lessening the severity of falls among older adults. This training can be proactive or reactive; however, the relative effectiveness of each and the necessary dosages are not known. The purpose of this research was to adapt an existing protocol for slip testing (reactive training) and video-game balance training (proactive) to better accommodate the abilities of older adults. We tested iteratively the initial protocols, set-ups, and equipment with a group of adults age 55 years and older and devised new protocols and equipment for each. After observing the subjects’ participation in the original protocol and taking into account their feedback, we made changes to four major areas of the protocol: the slipping protocol and equipment, the gaming surfaces, the harness, and the videogames themselves. We decreased the percentages for the slip distance and the slip weight in the slipping protocol, lessening the perturbation to better suit the physical abilities of older adults, and lengthened the slipping platform. We created three different gaming surfaces using mats and pool rafts, each with a distinct level of balance difficulty. A new harness was implemented into the protocol, one that allows for a wider range of stepping motion. Lastly, we modified the videogames, adding special rules and instructions that encouraged the subjects to play more aggressively while still remaining safe.https://engagedscholarship.csuohio.edu/u_poster_2015/1023/thumbnail.jp