A Fair Power Domain for Actor Computations

This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of Technology. Support for the laboratory's artificial intelligence research is provided in part by the Office of Naval Research of the Department of Defense under Contract N00014-75-C-0522.Actor-based languages feature extreme concurrency, allow side effects, and specify a form of fairness which permits unbounded nondeterminism. This makes it difficult to provide a satisfactory mathematical foundation for the semantics. Due to the high degree of parallelism, an oracle semantics would be intractable. A weakest precondition semantics is out of the question because of the possibility of unbounded nondeterminism. The most attractive approach, fixed point semantics using power domains, has not been helpful because the available power domain constructions, although very general, seemed to deal inadequately with fairness. By taking advantage of the relatively complex structure of the actor computation domain C, however, a power domain P(C) can be defined which is similar to Smyth's weak power domain but richer. Actor systems, which are collections of mutually recursive primitive actors with side effects, may be assigned meanings as least fixed points of their associated continuous functions acting on this power domain. Given a denotation A ∈ P(C), the set of possible complete computations of the actor system it represents is the set of least upper bounds of a certain set of "fair" chain in A, and this set of chains is definable within A itself without recourse to oracles or an auxiliary interpretive semantics. It should be emphasized that this power domain construction is not nearly as generally applicable as those of the Plotkin [Pl] and Smyth [Sm], which can be used with any complete partial order. Fairness seems to require that the domain from which the power domain is to be constructed contain sufficient operational information.Department of Defense Office of Naval Researc

Global Time in Actor Computations

This research was supported by a National Science Foundation Graduate Fellowship in mathematics.MIT Artificial Intelligence Laboratory National Science Foundatio

The Development and Use of Learning - Skill Centers in the Bible Schools

https://digitalcommons.acu.edu/crs_books/1430/thumbnail.jp

Processes Utilized by High School Students Reading Scientific Text

In response to an increased emphasis on disciplinary literacy in the secondary science classroom, an investigation of the literacy processes utilized by high school students while reading scientific text was undertaken. A think-aloud protocol was implemented to collect data on the processes students used when not prompted while reading a magazine article and a selection from a textbook. Following the think-aloud, participants provided an oral summary that was analyzed for content and quality to assess the effectiveness of the strategies. The data showed that familiarity with text structure and prior knowledge of the content affected the processes utilized. Differences between groups (frustration, instructional, and independent levels) were noted in reading both texts. Overall, participants made references to graphics but did not rely on the content of the graphics for clarification purposes. Group differences included the amount of attention given to content vocabulary; independent level readers spent more time previewing and reviewing vocabulary. Summary scores indicated that instructional level participants used processes most effectively. Frustration level readers demonstrated the ability to utilize a variety of processes through one-time use. Findings suggested: 1) increasing instruction on interpretation of graphics; 2) providing students with varied forms of scientific text; 3) focus on teaching strategies to frustration level readers; 4) encouraging summarization activities in the classroom; and 5) using multiple forms of assessment to identify disciplinary literacy processes

Hagiographic Bandit Slippages: Gaucho Gil in Music and Prose

This article examines representations of the Argentine folk saint Gauchito Gil in music and prose as Gil veneration spreads from the Argentine littoral to more urban and para-urban spaces. The movement in space and through genres reflects the play between the hegemonic and the vernacular and the closing of the frontier. First, the article considers Gauchito devotion as a subculture and analyses the production and maintenance of that subculture through chamamés. I argue that Orlando Van Bredam’s novella, El retobado: vida, pasión y muerte del Gauchito Gil, is a textualization of the vernacular devotion practiced by Gil devotees and slips between the novelistic and hagiographic modes. Building from Emilio Willems suggestion that marginal urban neighborhoods constitute an “anonymous frontier,” I then examine the mapping of Gil worship into urban spaces in cumbia villera and stories by Mariana Enríquez. Finally, I address the increasing institutionalization of Gauchito devotion.Este artículo examina representaciones del santo vernáculo argentino Gauchito Gil en música y prosa y el movimiento de su veneración desde el litoral argentino hacia espacios urbanos y periurbanos. Este desplazamiento tanto en el espacio como en los géneros refleja la interacción entre lo hegemónico y lo vernáculo, así como el cierre de la frontera. El artículo considera el culto del Gauchito como una subcultura y analiza la producción y preservación de dicha subcultura a través de chamamé. Sostenemos que la novela corta El retobado: vida, pasión y muerte del Gauchito Gil de Orlando Van Bredam es una textualización de la devoción vernácula practicada por los devotos al culto del Gauchito, y se desliza entre los modos novelescos y hagiográficos. Partiendo del planteamiento de Emilio Willems de que los barrios marginales urbanos son una “frontera anónima,” Examinamos cómo el culto de Gil se incorpora en el espacio urbano en la cumbia villera y en los cuentos de Mariana Enríquez. Finalmente, abordamos la curiosa ausencia del Guachito en El guacho Martín Fierro, la reescritura villera de Martín Fierro por Oscar Fariña, considerando su omisión de la epopeya como un síntoma de la institucionalización del culto del Gauchito

Existential witness extraction in classical realizability and via a negative translation

We show how to extract existential witnesses from classical proofs using Krivine's classical realizability---where classical proofs are interpreted as lambda-terms with the call/cc control operator. We first recall the basic framework of classical realizability (in classical second-order arithmetic) and show how to extend it with primitive numerals for faster computations. Then we show how to perform witness extraction in this framework, by discussing several techniques depending on the shape of the existential formula. In particular, we show that in the Sigma01-case, Krivine's witness extraction method reduces to Friedman's through a well-suited negative translation to intuitionistic second-order arithmetic. Finally we discuss the advantages of using call/cc rather than a negative translation, especially from the point of view of an implementation.Comment: 52 pages. Accepted in Logical Methods for Computer Science (LMCS), 201

The program is the model: Enabling [email protected]

The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-642-36089-3_7Revised Selected Papers of 5th International Conference, SLE 2012, Dresden, Germany, September 26-28, 2012The increasing application of Model-Driven Engineering in a wide range of domains, in addition to pure code generation, raises the need to manipulate models at runtime, as part of regular programs. Moreover, certain kinds of programming tasks can be seen as model transformation tasks, and thus we could take advantage of model transformation technology in order to facilitate them. In this paper we report on our works to bridge the gap between regular programming and model transformation by enabling the manipulation of Java APIs as models. Our approach is based on the specification of a mapping between a Java API (e.g., Swing) and a meta-model describing it. A model transformation definition is written against the API meta-model and we have built a compiler that generates the corresponding Java bytecode according to the mapping. We present several application scenarios and discuss the mapping between object-oriented meta-modelling and the Java object system. Our proposal has been validated by a prototype implementation which is also contributed.Work funded by the Spanish Ministry of Economy and Competitivity (TIN2011-24139), and the R&D programme of Madrid Region (S2009/TIC-1650)

A Church Built on Charity: Augustine\u27s Ecclesiology

This thesis will undertake the mission of articulating the ecclesiological thought of Augustine with particular emphasis on charity as the fundamental component to church unity. Hopefully, this will further demonstrate his inclusivity, not exclusivity. The beginnings of this thesis will simply show his influences, and thus serve as a background to understanding the mind of Augustine. The next step will take the reader into the world of Augustine’s theology of charity. Charity in the Christian life is the result of being gifted with God’s grace; how charity works and how proper, authentic charity appears will be the topic of the section. The second section of this thesis will concern itself with Donatism and Augustine’s ecclesiology. It will examine multiple complementary views of Church held by Augustine: mystical communion, Body of Christ, field hospital, etc., and demonstrate where charity exists and why its existence is crucial for church unity. The final chapter will explore Augustine’s mature theology of nature and grace, in order to reflect his universal sense of a need for grace that sets everyone on the same level

Continuation-Passing C: compiling threads to events through continuations

In this paper, we introduce Continuation Passing C (CPC), a programming language for concurrent systems in which native and cooperative threads are unified and presented to the programmer as a single abstraction. The CPC compiler uses a compilation technique, based on the CPS transform, that yields efficient code and an extremely lightweight representation for contexts. We provide a proof of the correctness of our compilation scheme. We show in particular that lambda-lifting, a common compilation technique for functional languages, is also correct in an imperative language like C, under some conditions enforced by the CPC compiler. The current CPC compiler is mature enough to write substantial programs such as Hekate, a highly concurrent BitTorrent seeder. Our benchmark results show that CPC is as efficient, while using significantly less space, as the most efficient thread libraries available.Comment: Higher-Order and Symbolic Computation (2012). arXiv admin note: substantial text overlap with arXiv:1202.324