4,911 research outputs found
Test-Case Reduction via Test-Case Generation: Insights from the Hypothesis Reducer (Tool Insights Paper)
No full textWe describe internal test-case reduction, the method of test-case reduction employed by Hypothesis, a widely-used property-based testing library for Python. The key idea of internal test-case reduction is that instead of applying test-case reduction externally to generated test cases, we apply it internally, to the sequence of random choices made during generation, so that a test case is reduced by continually re-generating smaller and simpler test cases that continue to trigger some property of interest (e.g. a bug in the system under test). This allows for fully generic test-case reduction without any user intervention and without the need to write a specific test-case reducer for a particular application domain. It also significantly mitigates the impact of the test-case validity problem, by ensuring that any reduced test case is one that could in principle have been generated. We describe the rationale behind this approach, explain its implementation in Hypothesis, and present an extensive evaluation comparing its effectiveness with that of several other test-case reducers, including C-Reduce and delta debugging, on applications including Python auto-formatting, C compilers, and the SymPy symbolic math library. Our hope is that these insights into the reduction mechanism employed by Hypothesis will be useful to researchers interested in randomized testing and test-case reduction, as the crux of the approach is fully generic and should be applicable to any random generator of test cases
Isrogrogidda Falka Af-soomaaliga: Aragti ku aadan Midaynta Qoraalkiisa
No full textQoraagu wuxuu diraasad ku sameeyey sidii loo midayn lahaa af Soomaaliga qoraaal ahaan loo adeegsada. Gaar ahaan wuxuu diiradda saarayaa sidii loo midayn lahaa qaababka isrogrogga falalka oo haatan loo adeegsado siyaabo aan midaysanayn.In questo articolo, l'autore analizza e avanza una proposta relativamente alla standardizzazione del somalo scritto, in particolar modo delle forme di coniugazione dei verbi somali che attualmente non sono scritte in modo omogenea.In this article, the author analyzes and provides a proposal about the standardization of written Somali, in particular relating to verb conjugation forms whose orthography still differs today.Cabdirashid M. Ismaaciil, Cabdalla C. Mansuur, Saynab A. Sharci (eds.
Coastal Research and its Economic Justification
No full textProper and thorough planning of coastal engineering projects is discussed and the economie justification of research work indicated. Examples are given concerning navigational problems, coastal protection problems, and harbor sediment problems.KWP-collectio
Midaynta iyo Horumarinta Af-soomaaliga
No full textQoraagu wuxuu maqaalkan ku falanqaynayaa arrimo ku saabsan midaynta af Soomaaliga qoran, oo dadka qaarkood ay ku doodaan in ay dhibaato ka taagantahay, iyagoo u aanaynaya kala duwanaanta lahjadaha Soomaaliyeed iyo farta af Soomaaliga oo aan xasillayn. Qoraha oo soo bandhigayaa in arrimahaasu aanu sax ahayn, wuxuuna muujinayaa caqabadaha dhabta ah ee hortaagan houmarinta af Soomaaliga: afku wuxuu la'yahay dawlad si rasmi ah u adeegsato, weerar ba'anna waxaa ku haya af Ingiriisiga, xagga ereyadana nabaadguur xooggan ayaa ku dhacaya, gaar ahaan ereyada la xiriira dhaqanka Soomaaliyeed.L'autore, in questo articolo, analizzando la questione della lingua somala scritta, cerca di illustrare che la situazione del somalo standard non è cosi problematica come a detta di alcuni somali, specialmente, nell'ortografia e nella differenza tra i dialetti, ma il problema somalo è bensì riscontrabile in altri fattori: la mancanza di un stato che continui ad adottare il somalo come lingua ufficiale, l'estinzione di tantissimi vocaboli in disuso, nonché la forte influenza dalla lingua inglese.The author in this article, in analysing the written somali language, wants to show the somali standard situation is not so bad, like some Somalis say, especially in orthography and in vernaculars difference. In spite of, the somali language problem is recognisable in some others factors: lack of state that usually chooses somali language as official language, extinction of many terms in disuse and also the strong influence of English.Cabdirashid M. Ismaaciil, Cabdalla C. Mansuur, Saynab A. Sharci (eds.
Putting Randomized Compiler Testing into Production (Experience Report)
No full textWe describe our experience over the last 18 months on a compiler testing technology transfer project: taking the GraphicsFuzz research project on randomized metamorphic testing of graphics shader compilers, and building the necessary tooling around it to provide a highly automated process for improving the Khronos Vulkan Conformance Test Suite (CTS) with test cases that expose fuzzer-found compiler bugs, or that plug gaps in test coverage. We present this tooling for test automation - gfauto - in detail, as well as our use of differential coverage and test case reduction as a method for automatically synthesizing tests that fill coverage gaps. We explain the value that GraphicsFuzz has provided in automatically testing the ecosystem of tools for transforming, optimizing and validating Vulkan shaders, and the challenges faced when testing a tool ecosystem rather than a single tool. We discuss practical issues associated with putting automated metamorphic testing into production, related to test case validity, bug de-duplication and floating-point precision, and provide illustrative examples of bugs found during our work
Om inloppet ifrån Östersjön : till SöderTelje eller Egelsta wiken
No full textAuthor: Nathanael Gerhard af Schultén.Dated: "Carlberg den 12 Januari 1806."Digital reproduction, The National Library of Finland, Centre for Preservation and Digitisation, MikkeliA description of the Baltic Sea.TravelEuropeanaSchultén, Nathanael Gerhard af (1750-1825
Dwing als gebiedsontwikkelaar een duidelijke opdracht af
No full textTerwijl de context waarin gebiedsontwikkelaars werken alleen maar complexer wordt, ziet Co Verdaas, hoogleraar gebiedsontwikkeling, een aanhoudende neiging om keuzes vooruit te schuiven of te verhullen. Hij geeft zes tips om gebiedsontwikkelaars in hun kracht te zetten. “Zonder escalatie geen resultaat zou het devies moeten zijn.”Practice Chair Urban Area Developmen
Mineral dissolution in silicate melts
No full textQuartz and orthopyroxene in mafic rocks are commonly observed to be
surrounded by fringes of granular pyroxene, and of olivine and clinopyroxene,
respectively. This study reproduces the conditions of formation of these textures,
and investigates their origins, kinetics and phase relations.
Pieces of silica glass or crystals of orthopyroxene were dissolved into
tholeiitic and slightly alkaline basalts, suspended from wire loops in an atmospheric
pressure quenching furnace, and run for 10 minutes to 32 days at subliquidus
temperatures between 1120° and 1190°C and oxygen fugacities close to the QFM
buffer. Polished sections of charges were examined primarily by backscattered
electron imagery and by microprobe analysis.
The textures developed in silica dissolution experiments consist of fringes
of elongate skeletal pyroxenes radially arranged around the silica. The pyroxenes
first nucleate on the surface of the silica. As dissolution continues, growth
continues mostly on existing crystals, rather than by the nucleation of additional
crystals.
Dissolution rates for silica range from 2.8*10⁻¹¹ to 4.4*10⁻¹⁰ms⁻¹, and are
time-independent until growth of the pyroxene fringe hinders transport processes in
the melt. This causes dissolution to slow down, until it ceases altogether after 3 to
8 days. A silica-rich layer of melt forms around the surface of charges run at higher
temperatures, suggesting that convection driven by variations in surface tension
may operate in the charges.
The textures developed in orthopyroxene dissolution experiments consist of
granular olivines, some of which nucleate on the pyroxene surface, whereas
others nucleate within the pyroxene as a result of the decomposition of included
phases. With time, olivine crystals become connected and form complex grain
shapes.
Dissolution rates for orthopyroxene range from 1.7*10⁻¹¹ to 1.2*10⁻⁹ ms⁻¹.
At higher temperatures dissolution rates are constant, but at lower temperatures
dissolution is time-dependent. Unlike silica dissolution, orthopyroxene dissolution
does not cease as a result of continued neocryst growth hindering melt transport,
indicating that the fringe remains permeable.
For both systems, the neocryst compositions are strongly dependent on the
chemistry of the melt formed at the interface between the dissolving crystal and the
bulk melt, and the neocrysts may be metastable with respect to the bulk melt.
Chemical equilibration of olivine neocrysts with time is observed for longer
experiments. Textural equilibration of olivine grains occurs by the processes of
liquid-phase sintering in runs longer than 12 hours.
Subliquidus dissolution data are applied to textures from natural samples
collected from dykes, lava flows and lava lakes, to estimate the residence time of
reacted crystals; values range from 0.6 to 208 days for reacted quartz, and from
0.7 to 462 days for reacted orthopyroxenes. The rates of cooling of the magma and
the size of the magma body in which the reaction occurred are also estimated
GPU Schedulers: How Fair Is Fair Enough?
No full textBlocking synchronisation idioms, e.g. mutexes and barriers, play an important role in concurrent programming. However, systems with semi-fair schedulers, e.g. graphics processing units (GPUs), are becoming increasingly common. Such schedulers provide varying degrees of fairness, guaranteeing enough to allow some, but not all, blocking idioms. While a number of applications that use blocking idioms do run on today's GPUs, reasoning about liveness properties of such applications is difficult as documentation is scarce and scattered.
In this work, we aim to clarify fairness properties of semi-fair schedulers. To do this, we define a general temporal logic formula, based on weak fairness, parameterised by a predicate that enables fairness per-thread at certain points of an execution. We then define fairness properties for three GPU schedulers: HSA, OpenCL, and occupancy-bound execution. We examine existing GPU applications and show that none of the above schedulers are strong enough to provide the fairness properties required by these applications. It hence appears that existing GPU scheduler descriptions do not entirely capture the fairness properties that are provided on current GPUs. Thus, we present two new schedulers that aim to support existing GPU applications. We analyse the behaviour of common blocking idioms under each scheduler and show that one of our new schedulers allows a more natural implementation of a GPU protocol
Simple risk model predicts incidence of atrial fibrillation in a racially and geographically diverse population: the CHARGE-AF consortium
No full textFull author list omitted for brevity. For the full list of authors, see article.BACKGROUND: Tools for the prediction of atrial fibrillation (AF) may identify high-risk individuals more likely to benefit from preventive interventions and serve as a benchmark to test novel putative risk factors. METHODS AND RESULTS: Individual-level data from 3 large cohorts in the United States (Atherosclerosis Risk in Communities [ARIC] study, the Cardiovascular Health Study [CHS], and the Framingham Heart Study [FHS]), including 18 556 men and women aged 46 to 94 years (19% African Americans, 81% whites) were pooled to derive predictive models for AF using clinical variables. Validation of the derived models was performed in 7672 participants from the Age, Gene and Environment-Reykjavik study (AGES) and the Rotterdam Study (RS). The analysis included 1186 incident AF cases in the derivation cohorts and 585 in the validation cohorts. A simple 5-year predictive model including the variables age, race, height, weight, systolic and diastolic blood pressure, current smoking, use of antihypertensive medication, diabetes, and history of myocardial infarction and heart failure had good discrimination (C-statistic, 0.765; 95% CI, 0.748 to 0.781). Addition of variables from the electrocardiogram did not improve the overall model discrimination (C-statistic, 0.767; 95% CI, 0.750 to 0.783; categorical net reclassification improvement, -0.0032; 95% CI, -0.0178 to 0.0113). In the validation cohorts, discrimination was acceptable (AGES C-statistic, 0.664; 95% CI, 0.632 to 0.697 and RS C-statistic, 0.705; 95% CI, 0.664 to 0.747) and calibration was adequate. CONCLUSION: A risk model including variables readily available in primary care settings adequately predicted AF in diverse populations from the United States and Europe
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