Forward Communication Only Placements and Their Use for Parallel Program Construction

AbstractA commonly used approach to develop deterministic parallel programs is to augment a sequential program with compiler directives that indicate which program blocks may potentially be executed in parallel. This paper develops a verification technique to reason about such compiler directives, in particular to show that they do not change the behaviour of the program. Moreover, the verification technique is tool-supported and can be combined with proving functional correctness of the program. To develop our verification technique, we propose a simple intermediate representation (syntax and semantics) that captures the main forms of deterministic parallel programs. This language distinguishes three kinds of basic blocks: parallel, vectorised and sequential blocks, which can be composed using three different composition operators: sequential, parallel and fusion composition. We show how a widely used subset of OpenMP can be encoded into this intermediate representation. Our verification technique builds on the notion of iteration contract to specify the behaviour of basic blocks; we show that if iteration contracts are manually specified for single blocks, then that is sufficient to automatically reason about data race freedom of the composed program. Moreover, we also show that it is sufficient to establish functional correctness on a linearised version of the original program to conclude functional correctness of the parallel program. Finally, we exemplify our approach on an example OpenMP program, and we discuss how tool support is provided.

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Research on the Promotion Path of Teachers’ Scientific Research and Innovation Ability based on Big Data Analysis of “Double High Program” Construction

Journal of Physics Conference Series ◽

10.1088/1742-6596/1744/4/042093 ◽

2021 ◽

Vol 1744 (4) ◽

pp. 042093

Author(s):

Yuanzhi Huang

Keyword(s):

Big Data ◽

Data Analysis ◽

Scientific Research ◽

Big Data Analysis ◽

Research And Innovation ◽

Innovation Ability ◽

Program Construction

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A Classification and Closure Properties of Languages for Describing Concurrent System Behaviours

Fundamenta Informaticae ◽

10.3233/fi-1981-4305 ◽

1981 ◽

Vol 4 (3) ◽

pp. 531-549 ◽

Cited By ~ 1

Author(s):

Miklós Szijártó

Keyword(s):

Formal Languages ◽

Parallel Program ◽

Sufficient Condition ◽

Necessary And Sufficient Condition ◽

Concurrent System ◽

Closure Properties ◽

Sequential Program ◽

Necessary And Sufficient ◽

Special Case ◽

Independence Relations

The correspondence between sequential program schemes and formal languages is well known (Blikle and Mazurkiewicz (1972), Engelfriet (1974)). The situation is more complicated in the case of parallel program schemes, and trace languages (Mazurkiewicz (1977)) have been introduced to describe them. We introduce the concept of the closure of a language on a so called independence relation on the alphabet of the language, and formulate several theorems about them and the trace languages. We investigate the closedness properties of Chomsky classes under closure on independence relations, and as a special case we derive a new necessary and sufficient condition for the regularity of the commutative closure of a language.

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Astrometric Radial Velocities From Hipparcos

Highlights of Astronomy ◽

10.1017/s153929960002219x ◽

1998 ◽

Vol 11 (1) ◽

pp. 564-564

Author(s):

D. Dravins ◽

L. Lindegren ◽

S. Madsen ◽

J. Holmberg

Keyword(s):

Radial Velocity ◽

High Precision ◽

Radial Velocities ◽

Radial Motion ◽

Spectral Lines ◽

Parallel Program ◽

Stellar Surface ◽

Space Astrometry ◽

Stellar Motion ◽

Surface Convection

Abstract Space astrometry now permits accurate determinations of stellar radial motion, without using spectroscopy. Although the feasibility of deducing astrometric radial velocities from geometric projection effects was realized already by Schlesinger (1917), only with Hipparcos has it become practical. Such a program has now been carried out for the moving clusters of Ursa Major, Hyades, and Coma Berenices. Realized inaccuracies reach about 300 m/s (Dravins et al. 1997). Discrepancies between astrometric and spectroscopic radial velocities reveal effects (other than stellar motion) that affect wavelength positions of spectral lines. Such are caused by stellar surface convection, and by gravitational redshifts. A parallel program (Gullberg & Dravins 1997) is analyzing high-precision spectroscopic radial velocities for different spectral lines in these stars, using the ELODIE radial-velocity instrument atHaute-Provence.

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A semiparametric method for the analysis of outcomes during a gap in HIV care under incomplete outcome ascertainment

Statistical Communications in Infectious Diseases ◽

10.1515/scid-2019-0013 ◽

2020 ◽

Vol 12 (s1) ◽

Author(s):

Giorgos Bakoyannis ◽

Lameck Diero ◽

Ann Mwangi ◽

Kara K. Wools-Kaloustian ◽

Constantin T. Yiannoutsos

Keyword(s):

Electronic Health Record ◽

East Africa ◽

Sub Saharan Africa ◽

Hiv Care ◽

Double Sampling ◽

Health Record ◽

Electronic Health Record Data ◽

Semiparametric Method ◽

Program Construction ◽

Electronic Health

AbstractObjectivesEstimation of the cascade of HIV care is essential for evaluating care and treatment programs, informing policy makers and assessing targets such as 90-90-90. A challenge to estimating the cascade based on electronic health record concerns patients “churning” in and out of care. Correctly estimating this dynamic phenomenon in resource-limited settings, such as those found in sub-Saharan Africa, is challenging because of the significant death under-reporting. An approach to partially recover information on the unobserved deaths is a double-sampling design, where a small subset of individuals with a missed clinic visit is intensively outreached in the community to actively ascertain their vital status. This approach has been adopted in several programs within the East Africa regional IeDEA consortium, the context of our motivating study. The objective of this paper is to propose a semiparametric method for the analysis of competing risks data with incomplete outcome ascertainment.MethodsBased on data from double-sampling designs, we propose a semiparametric inverse probability weighted estimator of key outcomes during a gap in care, which are crucial pieces of the care cascade puzzle.ResultsSimulation studies suggest that the proposed estimators provide valid estimates in settings with incomplete outcome ascertainment under a set of realistic assumptions. These studies also illustrate that a naïve complete-case analysis can provide seriously biased estimates. The methodology is applied to electronic health record data from the East Africa IeDEA Consortium to estimate death and return to care during a gap in care.ConclusionsThe proposed methodology provides a robust approach for valid inferences about return to care and death during a gap in care, in settings with death under-reporting. Ultimately, the resulting estimates will have significant consequences on program construction, resource allocation, policy and decision making at the highest levels.

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