Synthesis of Petri Nets with Localities

Automated synthesis from behavioural specifications is an attractive way of constructing computational systems. In this paper, we look at a specific instance of this approach which aims at constructing GALS (globally asynchronous locally synchronous) systems. GALS systems are represented by Petri nets with localities, each locality defining a set of co-located actions, and specifications are given in terms of transition systems with arcs labelled by steps of executed actions. The proposed synthesis procedures are based on the regions of transition systems, and work without knowing which actions are to be co-located. We consider two basic classes of Petri nets, viz. Elementary Net System with Localities (ENL-system) and Place/Transition nets with localities (PTL-nets). In particular, we discuss ENL-systems where there is no conflict between events coming from different localities. In such a case, the synthesis problem reduces to checking just one co-location relation. This result is then extended to PTL-nets

Membrane Systems and Petri Net Synthesis

Automated synthesis from behavioural specifications is an attractive and powerful way of constructing concurrent systems. Here we focus on the problem of synthesising a membrane system from a behavioural specification given in the form of a transition system which specifies the desired state space of the system to be constructed. We demonstrate how a Petri net solution to this problem, based on the notion of region of a transition system, yields a method of automated synthesis of membrane systems from state spaces.Comment: In Proceedings MeCBIC 2012, arXiv:1211.347

Connected by 25: Effective Policy Solutions for Vulnerable Youth Issue Brief

In an effort to strengthen philanthropic investments among its membership, the Youth Transition Funders Group (YTFG) asked a group of policy experts to provide recommendations on how foundations can work to encourage effective policy solutions on issues affecting youth in transition to adulthood. The primary challenge was to think beyond the systemic silos that so deeply shape the services and expectations of youth and move towards an overall framework that could produce improved outcomes. YTFG's work is based on the Connected by 25 framework, in which all youth reach the following outcomes by age 25: Educational achievement in preparation for career and community participation, including a high school diploma, post-secondary degree, and/or vocational certificate trainingGainful employment and/or access to career training to achieve life-long economic successConnections to a positive support system -- namely, guidance from family members and caring adults, as well as access to health, counseling, and mental health servicesThe ability to be a responsible and nurturing parentThe capacity to be actively engaged in the civic life of one's community This issue brief offers a summary of those recommendations, focusing on four primary transition points that often threaten the ability for youth to be connected by age 25 to the institutions and support systems that help them succeed throughout life

Beyond similarity: A network approach for identifying and delimiting biogeographical regions

Biogeographical regions (geographically distinct assemblages of species and communities) constitute a cornerstone for ecology, biogeography, evolution and conservation biology. Species turnover measures are often used to quantify biodiversity patterns, but algorithms based on similarity and clustering are highly sensitive to common biases and intricacies of species distribution data. Here we apply a community detection approach from network theory that incorporates complex, higher order presence-absence patterns. We demonstrate the performance of the method by applying it to all amphibian species in the world (c. 6,100 species), all vascular plant species of the USA (c. 17,600), and a hypothetical dataset containing a zone of biotic transition. In comparison with current methods, our approach tackles the challenges posed by transition zones and succeeds in identifying a larger number of commonly recognised biogeographical regions. This method constitutes an important advance towards objective, data derived identification and delimitation of the world's biogeographical regions.Comment: 5 figures and 1 supporting figur

Vulnerable Youth: Background and Policies

[Excerpt] This report first provides an overview of the youth population and the increasing complexity of transitioning to adulthood for all adolescents. It also provides a separate discussion of the concept of “disconnectedness,” as well as the protective factors youth can develop during childhood and adolescence that can mitigate poor outcomes. Further, the report describes the evolution of federal youth policy, focusing on three time periods, and provides a brief overview of current federal programs targeted at vulnerable youth. (Table A 1 at the end of the report, enumerates the objectives and funding levels of such programs. Note that the table does not enumerate all programs that target, even in small part, vulnerable or disconnected youth.) The report then discusses the challenges of coordinating federal programs for youth, as well as federal legislation and initiatives that promote coordination among federal agencies and support programs with a positive youth development focus

The Effect of Mandated State Education Spending on Total Local Resources (new title: The effect of state education finance reform on total local resources)

Many states are under court-order to reduce local disparities in education spending. While a substantial body of literature suggests that these orders and the resulting school finance equalizations have increased the level and progressivity of state education spending, there is little evidence on the broader effects of such measures on the change in total resources available not only for schools, but for other local government programs as well. When states spend more on education, both state and local budget constraints change. We find that while mandated school finance equalizations increase both the level and progressivity of state spending on education, states finance the required increase in education spending in part by reducing their aid to localities for other programs. Local governments, in turn, respond to the increases in state taxation and spending by reducing both their own revenue-raising and their own spending on education and on other programs. Thus, while state education aid does increase total spending on education, it does so at the expense of drawing resources away from spending on programs like public welfare, highways, and hospitals. These findings provide insight into the effectiveness of using earmarked funds to achieve redistribution.school finance equalization, state and local public finance

Putting a Price Tag on the Common Core: How Much Will Smart Implementation Cost?

The Common Core State Standards (CCSS) for English language arts and mathematics represent a sea change in standards-based reform and their implementation is the movement's next -- and greatest -- challenge. Yet, while most states have now set forth implementation plans, these tomes seldom address the crucial matter of cost. Putting a Price Tag on the Common Core: How Much Will Smart Implementation Cost? estimates the implementation cost for each of the forty-five states (and the District of Columbia) that have adopted the Common Core State Standards and shows that costs naturally depend on how states approach implementation. Authors Patrick J. Murphy of the University of San Francisco and Elliot Regenstein of EducationCounsel LLC illustrate this with three models

Mobile Synchronizing Petri Nets: A Choreographic Approach for Coordination in Ubiquitous Systems

AbstractThe term Ubiquitous Computing was coined by Mark Weiser almost two decades ago. Despite all the time that has passed since Weiser's vision, ubiquitous computing still has a long way ahead to become a pervasive reality. One of the reasons for this may be the lack of widely accepted formal models capable of capturing and analyzing the complexity of the new paradigm. We propose a simple Petri Net based model to study some of its main characteristics. We model both devices and software components as a special kind of coloured Petri Nets, located in locations, that can move to other locations and synchronize with other co-located nets, offering and requesting services. We obtain an amenable model for ubiquitous computing, due to its graphical representation. We present our proposal in a progressive way, first presenting a basic model where coordination is formalized by the synchronized firing of pairs of compatible transitions that offer and request a specific service, and ad hoc networks are modeled by constraining mobility by the dynamic acquisition of locality names. Next, we introduce a mechanism for the treatment of robust security properties, namely the generation of fresh private names, to be used for authentication properties