Using automata to characterise fixed point temporal logics

This work examines propositional fixed point temporal and modal logics called mu-calculi and their relationship to automata on infinite strings and trees. We use correspondences between formulae and automata to explore definability in mu-calculi and their fragments, to provide normal forms for formulae, and to prove completeness of axiomatisations. The study of such methods for describing infinitary languages is of fundamental importance to the areas of computer science dealing with non-terminating computations, in particular to the specification and verification of concurrent and reactive systems. To emphasise the close relationship between formulae of mu-calculi and alternating automata, we introduce a new first recurrence acceptance condition for automata, checking intuitively whether the first infinitely often occurring state in a run is accepting. Alternating first recurrence automata can be identified with mu-calculus formulae, and ordinary, non-alternating first recurrence automata with formulae in a particular normal form, the strongly aconjunctive form. Automata with more traditional Büchi and Rabin acceptance conditions can be easily unwound to first recurrence automata, i.e. to mu-calculus formulae. In the other direction, we describe a powerset operation for automata that corresponds to fixpoints, allowing us to translate formulae inductively to ordinary Büchi and Rabin-automata. These translations give easy proofs of the facts that Rabin-automata, the full mu-calculus, its strongly aconjunctive fragment and the monadic second-order calculus of n successors SnS are all equiexpressive, that Büchi-automata, the fixpoint alternation class Pi_2 and the strongly aconjunctive fragment of Pi_2 are similarly related, and that the weak SnS and the fixpoint-alternation-free fragment of mu-calculus also coincide. As corollaries we obtain Rabin's complementation lemma and the powerful decidability result of SnS. We then describe a direct tableau decision method for modal and linear-time mu-calculi, based on the notion of definition trees. The tableaux can be interpreted as first recurrence automata, so the construction can also be viewed as a transformation to the strongly aconjunctive normal form. Finally, we present solutions to two open axiomatisation problems, for the linear-time mu-calculus and its extension with path quantifiers. Both completeness proofs are based on transforming formulae to normal forms inspired by automata. In extending the completeness result of the linear-time mu-calculus to the version with path quantifiers, the essential problem is capturing the limit closure property of paths in an axiomatisation. To this purpose, we introduce a new \exists\nu-induction inference rule

Reports Of Conferences, Institutes, And Seminars

This quarter\u27s column offers coverage of multiple sessions from the 2016 Electronic Resources & Libraries (ER&L) Conference, held April 3–6, 2016, in Austin, Texas. Topics in serials acquisitions dominate the column, including reports on altmetrics, cost per use, demand-driven acquisitions, and scholarly communications and the use of subscriptions agents; ERMS, access, and knowledgebases are also featured

Bearing witness : scaling people, place, and politics in the architectural models of West Mexico

Throughout Mesoamerica, artisans utilized small-scale figurines to create narrative scenes that crystallized ephemeral performance. While most of these scenes can be freely arranged and handled, examples from West Mexico stand apart. They are unique in their attention to not only place, but also people, as ornamented figurines are rooted within miniaturized representations of the built environment. Capturing dynamic moments in clay, these objects offer glimpses into an ancient region that has been negatively impacted by modernization, time, and heavy looting. Spectators witness pole-climbing rituals, feasting events, and mortuary processions, continuously observing how space contributed to communal gathering and participation. Unfortunately, this repeated emphasis upon communal gathering, in addition to the small-scale and limited provenience of the ceramics, have led scholars to dismiss the objects as potent forms of socio-political expression. Yet, as one of the few forms of material culture within West Mexico that contains not only figural representation, but narrative scenes, these maquettes must have embodied various modes of intimate knowledge for ancient peoples, just as they offer important insight for contemporary scholars. In this paper, I propose that the maquettes are not merely anecdotal forms, but objects that offer insight into the socio-political complexities of the region. In their emulation of people and place, they invite the spectator to mediate upon spaces that served as arenas for social performances and the socialized bodies that gathered within those spaces. Solidifying people, performance, and the built environment in clay, these tableau-like models stage the social relationships and interactions that were forged within public patio spaces. These maquettes invite investigation into questions of individuality and collectivity, social and ritual practices, and the ways in which architecture and action were both scaled up and scaled down in West Mexican artistic traditions

Needs Assessment to Improve Sepsis Bundle Compliance in the Emergency Department

Sepsis is a leading cause of morbidity and mortality worldwide. Treatment depends on time-sensitive antibiotic initiation, fluid resuscitation, and vasoactive support. Early recognition and bundled care are core tenets of management. Thus, this project aims to identify barriers to sepsis bundle compliance in a local community emergency department. Specifically, how do perceived barriers to sepsis bundle compliance as identified by staff correspond with quantitative delays in care as demonstrated by chart data? This mixed-methods needs assessment consists of staff surveys and analysis of extracted chart data. Staff surveys revealed barriers including staffing shortages, difficulty with intravenous (IV) access, and lack of recognition in triage. Case reviews showed that many patients receive components of the 1-hour sepsis bundle before they screen SIRS+ (57% of patients for lactate draws, 34% of patients for blood culture draws, n=35). Across cases, average door-to-antibiotic time was 137.06 minutes (SD 88.66 minutes). Thus, the department has yet to meet its target of door-to-antibiotic time less than one hour. Survey data and case reviews provide a launchpad for future quality improvement (QI) initiatives in the emergency department

Sublogics of a Branching Time Logic of Robustness

In this paper we study sublogics of RoCTL*, a recently proposed logic for specifying robustness. RoCTL* allows specifying robustness in terms of properties that are robust to a certain number of failures. RoCTL* is an extension of the branching time logic CTL* which in turn extends CTL by removing the requirement that temporal operators be paired with path quantifiers. In this paper we consider three sublogics of RoCTL*. We present a tableau for RoBCTL*, a bundled variant of RoCTL* that allows fairness constraints to be placed on allowable paths. We then examine two CTL-like restrictions of CTL*. Pair-RoCTL* requires a temporal operator to be paired with a path quantifier; we show that Pair-RoCTL* is as hard to reason about as the full CTL*. State-RoCTL* is restricted to State formulas, and we show that there is a linear truth preserving translation of State-RoCTL into CTL, allowing State-RoCTL to be reasoned about as efficiently as CTL

Can Standardizing CABG care with Clinical Pathways Reduce Length of Stay and Hospital Acquired Infections?

Clinical pathways are a common component in the quest to improve the quality of health. Clinical pathways are used to reduce variation, improve quality of care and maximize the outcomes for specific groups of patients (Lawal, et al., 2016). The purpose of this project is to develop and initiate a Coronary Artery Bypass Grafting (CABG) clinical pathway to reduce variation in care as a way to improve quality of care and patient outcomes for CABG patients CABG surgery is considered a high risk, high cost, yet highly profitable surgery with considerable post-operative complications that affect numerous quality metrics including Length of Stay (LOS), hospital acquired infections (HAI), mortality rate, readmission rates and patient satisfaction. The importance of delivering high quality clinical management of CABG patients and minimizing postoperative complications is essential for the growth of a Center of Excellence and for financial sustainability. Therefore, implementation of CABG Clinical Pathways (CPW) will improve quality of care delivered to patients who undergo coronary revascularization via CABG. As a result of the implementation of the CABG clinical pathway there was a reduction in HAI including central line associated blood stream infection, catheter associated urinary tract infection and surgical site infection. In addition to the reduction of HAI the CABG clinical pathway also presented an initial reduction in the LOS of CABG patients

Patterns of Resource Integration in the Self-service Approach to Business Analytics

The main premise of Self-Service Business Analytics (SSBA) is to make business users autonomous during the data analytical process. To empower business employees, organisations are decentralising their analytical capabilities therefore adopting an SSBA approach. Yet, little is known about how employees integrate resources, such as personal competencies, environment resources including technology, and other employees’ competencies, to generate insights in SSBA. Based on the empirical data of a major Norwegian online marketplace and drawing on service-dominant logic as an analytical framework, we identify and explain two types of resource integration in an SSBA environment: direct and clustered recourse integration (including 1st tier and 2nd tier) enabled and controlled by three types of institutions. We finally discuss some organisational implications and the meaning of each sub-type of clustered resource integration

MODELISATION DE SYSTEMES DE PRODUCTION ORIENTES SERVICES

International audienceCet article traite de la problématique de la servicisation : transition de modèle d'entreprise depuis un modèle d'entreprise de production de bien, vers un modèle basé sur la production couplée de biens et de services. Après avoir situé les enjeux de cette transformation économique et organisationnelle, nous proposons une démarche de modélisation des systèmes de production orientés services, puis nous approfondissons la modélisation d'un sous-système spécifique : le système d'usage. Nous présentons un modèle conceptuel du système d'usage, puis une application industrielle mettant en évidence une implémentation de ce modèle, destinée à une étude par simulation