A Coalgebraic Semantics for Imperative Programming Languages

In the theory of programming languages, one often takes two complementary perspectives. In operational semantics, one defines and reasons about the behaviour of programs; and in denotational semantics, one abstracts away implementation details, and reasons about programs as mathematical objects or denotations. The denotational semantics should be compositional, meaning that denotations of programs are determined by the denotations of their parts. It should also be adequate with respect to operational equivalence: programs with the same denotation should be behaviourally indistinguishable. One often has to prove adequacy and compositionality independently for different languages, and the proofs are often laborious and repetitive. These proofs were provided systematically in the context of process algebras by the mathematical operational semantics framework of Turi and Plotkin – which represented transition systems as coalgebras, and program syntax by free algebras; operational specifications were given by distributive laws of syntax over behaviour. By framing the semantics on this abstract level, one derives denotational and operational semantics which are guaranteed to be adequate and compositional for a wide variety of examples. However, despite speculation on the possibility, it is hard to apply the framework to programming languages, because one obtains undesirably fine-grained behavioural equivalences, and unconventional notions of operational semantics. Moreover, the behaviour of these languages is often formalised in a different way – such as computational effects, which may be thought of as an interface between programs and external factors such as non-determinism or a variable store; and comodels, or transition systems which implement these effects. This thesis adapts the mathematical operational semantics framework to provide semantics for various classes of programming languages. After identifying the need for such an adaptation, we show how program behaviour may be characterised by final coalgebras in suitably order- enriched Kleisli categories. We define both operational and denotational semantics, first for languages with syntactic effects, and then for languages with effects and/or comodels given by a Lawvere theory. To ensure adequacy and compositionality, we define concrete and abstract operational rule-formats for these languages, based on the idea of evaluation-in-context; we give syntactic and then categorical proofs that those properties are guaranteed by operational specifications in these rule-formats.Open Acces

THE CLINICAL PROFILE AND CORONARY ARETERY FINDINGS IN PATIENTS WITH ATRIAL FIBRILLATION

Background: Atrial fibrillation (AF) is a common arrhythmia in daily practice and one of the heart disorders with the highest morbidity and death rates, as it is responsible for a huge number of negative consequences. In our country, there is limited information on the prevalence or natural history of the less well-defined clinical types. Objective: to evaluate the clinical profile and coronary artery findings in atrial fibrillation patients. Patients and Methods: This cross-sectional study was conducted during the period from the first of October 2019 to end of July 2021 at the Iraqi Center for the heart disease at Baghdad Medical City. Included 32 Iraqi patients with atrial fibrillation of both genders. Angiography performed through the femoral Artery approach, Data collected by history, through clinical examination and investigations, using data collection sheet Results: The main type of AF was chronic, (62.5%), Echocardiography findings revealed Systolic dysfunction in 31.1% of patients, Diastolic dysfunction in 37.5%, and both dysfunctions in 6.2%, Left atrium was dilated in 13 (40.6%). Angiographic findings revealed RCA lesion in 13 (40.6%) patients, LCA in 9 (28.1%) while both RCA and LCA lesions present in 3 (9.4%) patients. LAD lesions reported in 10 (31.2%) patients, LCX in 27.8% and LMS in 16.8%. Conclusion: Chronic AF was the more frequent type, Systolic and diastolic dysfunction are frequent among AF patients. RCA was more frequently affected than LCA, LAD was the more affected branch

Analisis Peningkatan Kapasitas Kantong Lahar Kali Regoyo Desa Regoyo Kabupaten Lumajang

Kali Regoyo menerima material dari letusan Gunung Semeru dengan volume ± 6 juta m3 atau hampir 10 %dari total perkiraan material yang menjadi lahar sekunder. Salah satu usaha yang dilakukan dalam rangka pengendalian aliran sedimen dan mengurangi suplai sedimen tersebut adalah dengan menahan dan menampung sehingga aliran lahar atau sedimen dalam relatif lama yang dapat mengakibatkan pendangkalan pada daerah tengah dan hilir. Untuk menghindari bencana yang diakibatkan oleh bahaya aliran lahar Gunung Semeru tersebut, dibuat bangunan pengendali sedimen yang antara lain Kantong Pasir. Untuk mereduksi debit puncak sedimen karena volume kontrol dapat direncanakan dengan menentukan dimensi dan jumlah celah. Dengan kata lain dimensi dan jumlah celah berpengaruh terhadap besar volume kontrol sedimen. Makin kecil dimensi celah dan makin sedikit jumlah celah, makin besar volume kontrol sedimen. Setelah debit puncak perencanaan (Q) sebesar 357,397 m3/det didapat dari perhitungan, maka dapat direncanakan dimensi drempel kantong lahar. Dari hasil perhitungan diperoleh bahwa tinggi main dam 6,5 m, lebar mercu main dam 4 m, kemiringan bagian hulu 1:0,9 dan kemiringan hilir 1:0,2, lebar dasar peluap 100 m, elevasi muka air 1,524 m dan tinggi jagaan 1,2. Tinggi sub dam 3,34 m, lebar mercu sub dam 3 m, kemiringan bagian hulu 1:0,9 dan kemiringan bagian hilir 1:0,2. Jarak main dam dan sub dam adalah 25 m dengan tebal lantai (Apron) 1,5 m, volume sedimen statis = 910.560,345 m3, volume sediment dinamis = 1.204.847,909 m3, volume sedimen yang harus diatur = 294.287,564 m3. Melihat begitu kompleksnya permasalahan sedimen dan perilakunya, maka penanggulangan terhadap kemungkinan terjadinya banjir lahar di daerah kali regoyo harus memperhatikan kondisi dan perilaku sedimen yang ada. Kata Kunci : Lahar, Sedimen, dan Drempel Kantong Lahar

Coalgebraic Aspects of Bidirectional Computation

We have previously (Bx, 2014; MPC, 2015) shown that several statebased bx formalisms can be captured using monadic functional programming, using the state monad together with possibly other monadic effects, giving rise to structures we have called monadic bx (mbx). In this paper, we develop a coalgebraic theory of state-based bx, and relate the resulting coalgebraic structures (cbx) to mbx. We show that cbx support a notion of composition coherent with, but conceptually simpler than, our previous mbx definition. Coalgebraic bisimulation yields a natural notion of behavioural equivalence on cbx, which respects composition, and essentially includes symmetric lens equivalence as a special case. Finally, we speculate on the applications of this coalgebraic perspective to other bx constructions and formalisms

Fuzzy-based collision avoidance system for autonomous driving in complicated traffic scenarios

Collision avoidance is an important requirement for safe and autonomous driving in modern transportation system. In this paper, we present a fuzzy based control approach for smart and safe obstacle avoidance in complicated traffic scenario where there are static and dynamic obstacles (e.g. broken-down vehicles, wrong parking road-side vehicles, or moving vehicles, etc.) The fuzzy system makes an optimal decision to control the car throttle, braking, and steering to avoid collision using the available information on the road map (i.e. the distance to obstacles, the current traffic in the neighbouring lanes, the velocity of the front and rear car, etc.). Simulation results from three different scenarios involving a combination of dynamic and static or broken-down vehicles show that the fuzzy controlled car can effectively avoid obstacle or collision in complicated traffic situations. ©2018 IEEE

Fuzzy based obstacle avoidance system for autonomous mobile robot

The goal of this research was to develop a fuzzy obstacle avoidance system for an autonomous mobile robot using IR detection sensors. This paper presents implemented control architecture for behavior-based mobile robot. The mobile robot is able to interact with an unknown environment using a reactive strategy determined by sensory information. Current research in robotics aims to build autonomous and intelligent robots, which can plan its motion in a dynamic environment. Autonomous mobile robots are increasingly used in well structured environment such as warehouses, offices and industries. Fuzzy behavior able to make inferences is well suited for mobile robot navigation because of the uncertainty of the environment. A rule-based fuzzy controller with reactive behavior was implemented and tested on a two wheels mobile robot equipped with infrared sensors to perform collision-free navigation. The experimental results have shown that the proposed architecture provides an efficient and flexible solution for small wheeled mobile robots