On the Learnability of Programming Language Semantics

This is the final version of the article. Available from ICE via the DOI in this record.Game semantics is a powerful method of semantic analysis for programming languages. It gives mathematically accurate models ("fully abstract") for a wide variety of programming languages. Game semantic models are combinatorial characterisations of all possible interactions between a term and its syntactic context. Because such interactions can be concretely represented as sets of sequences, it is possible to ask whether they can be learned from examples. Concretely, we are using long short-term memory neural nets (LSTM), a technique which proved effective in learning natural languages for automatic translation and text synthesis, to learn game-semantic models of sequential and concurrent versions of Idealised Algol (IA), which are algorithmically complex yet can be concisely described. We will measure how accurate the learned models are as a function of the degree of the term and the number of free variables involved. Finally, we will show how to use the learned model to perform latent semantic analysis between concurrent and sequential Idealised Algol

Voronoi-Based Archive Sampling for Robust Optimisation

This is the author accepted manuscript. The final version is available from ACM via the DOI in this recordWe propose a framework for estimating the quality of solutions in a robust optimisation setting by utilising samples from the search history and using MC sampling to approximate a Voronoi tessellation. This is used to determine a new point in the disturbance neighbourhood of a given solution such that – along with the relevant archived points – they form a well-spread distribution, and is also used to weight the archive points to mitigate any selection bias in the neighbourhood history. Our method performs comparably well with existing frameworks when implemented inside a CMA-ES on 9 test problems collected from the literature in 2 and 10 dimensions.This work was supported by the Engineering and Physical Sciences Research Council [grant number EP/N017846/1]

Optimisation and Landscape Analysis of Computational Biology Models: A Case Study

This is the author accepted manuscript. The final version is available from ACM via the DOI in this record.The parameter explosion problem is a crucial bottleneck in modelling gene regulatory networks (GRNs), limiting the size of models that can be optimised to experimental data. By discretising state, but not time, Boolean delay equations (BDEs) provide a signi ficant reduction in parameter numbers, whilst still providing dynamical complexity comparable to more biochemically detailed models, such as those based on differential equations. Here, we explore several approaches to optimising BDEs to timeseries data, using a simple circadian clock model as a case study. We compare the ffectiveness of two optimisers on our problem: a genetic algorithmf(GA) and an elite accumulative sampling (EAS) algorithm that provides robustness to data discretisation. Our results show that both methods are able to distinguish effectively between alternative architectures, yielding excellent ts to data. We also perform a landscape analysis, providing insights into the properties that determine optimiser performance (e.g. number of local optima and basin sizes). Our results provide a promising platform for the analysis of more complex GRNs, and suggest the possibility of leveraging cost landscapes to devise more effi cient optimisation schemes.This work was financially supported by the Engineering and Physical Sciences Research Council [grant numbers EP/N017846/1, EP/N014391/1], and made use of the Zeus and Isca supercomputing facilities provided by the University of Exeter HPC Strategy

Robust Optimisation using Voronoi-Based Archive Sampling

Engineering and Physical Sciences Research Council (EPSRC

Robust Multi-Modal Optimisation

Robust and multi-modal optimisation are two important topics that have received significant attention from the evolutionary computation community over the past few years. However, the two topics have usually been investigated independently and there is a lack of work that explores the important intersection between them. This is because there are real-world problems where both formulations are appropriate in combination. For instance, multiple ‘good’ solutions may be sought which are distinct in design space for an engineering problem – where error between the computational model queried during optimisation and the real engineering environment is believed to exist (a common justification for multi-modal optimisation) – but also engineering tolerances may mean a realised design might not exactly match the inputted specification (a robust optimisation problem). This paper conducts a preliminary examination of such intersections and identifies issues that need to be addressed for further advancement in this new area. The paper presents initial benchmark problems and examines the performance of combined state-of-the-art methods from both fields on these problems.This work was supported by the Engineering and Physical Sciences Research Council [grant number EP/N017846/1]

On the Exploitation of Search History and Accumulative Sampling in Robust Optimisation

This is the author accepted manuscript. The final version is available from ACM via the DOI in this record.Efficient robust optimisation methods exploit the search history when evaluating a new solution by using information from previously visited solutions that fall in the new solution’s uncertainty neighbourhood. We propose a full exploitation of the search history by updating the robust fitness approximations across the entire search history rather than a fixed population. Our proposed method shows promising results on a range of test problems compared with other approaches from the literature.This work was supported by the Engineering and Physical Sciences Research Council [grant number EP/N017846/1]

Landscape Analysis Under Measurement Error

This is the author accepted manuscript. The final version is available from ACM via the DOI in this recordThere are situations where the need for optimisation with a global precision tolerance arises — for example, due to measurement, numerical or evaluation errors in the objective function. In such situations, a global tolerance ε > 0 can be predefined such that two objective values are declared equal if the absolute difference between them is less than or equal to ε. This paper presents an overview of fitness landscape analysis under such conditions. We describe the formulation of common landscape categories in the presence of a global precision tolerance. We then proceed by dis- cussing issues that can emerge as a result of using tolerance, such as the increase in the neutrality of the fitness landscape. To this end, we propose two methods to exhaustively explore plateaus in such application domains — one of which is point-based and the other of which is set-based.Engineering and Physical Sciences Research Council (EPSRC

Post-tonsillectomy hemorrhage after bipolar diathermy vs. cold dissection surgical techniques in Alahsa region, Saudi Arabia

Introduction: Tonsillectomy is a common surgical procedure done by  totolaryngologists. Tonsillectomy is a relatively simple procedure. The concept of implementing it as a day case operation has become increasingly popular.Material and Methods: This is a cross sectional study done in Alahsa city, eastern province, Saudi Arabia during the period from January 2014 to March 2015,This study reported the postoperative hemorrhage after Bipolar diathermy and Cold dissection surgical techniques to evaluate the incidence of the hemorrhage and to identify the possible risk factors associated with its occurrence.Results: Postoperative bleeding occurred in 45 (3.6%) out of 1232 patients. Post-tonsillectomy hemorrhage according to operation technique was significantly higher among patients who underwent bipolar diathermy than cold dissection technique (p< 0.05).Conclusion: Bleeding after operation by bipolar diathermy technique was occurring more frequently within the first five days. Hemoglobin level was significantly decreased in posttonsillectomy hemorrhage

Ophthalmic short- and long-term outcomes for premature infants: Results of an extended follow-up program in Saudi Arabia

AbstractPurposeStudy the ophthalmic morbidities for infants born prematurely at a Tertiary care center in Riyadh city.MethodsRetrospective, longitudinal cohort study at King Fahad Medical City for premature infants born at gestational age (GA) ⩽32weeks or birth weight (BW) ⩽1500g during the study period from January 1, 2007, until the end of December 2009 was conducted. Short term outcome was diagnosis with Retinopathy of Prematurity (ROP) and long-term outcome was ophthalmic findings at age 18–24months.ResultsThe cumulative incidence of ROP was 30%. Infants diagnosed with ROP had a mean GA of 27weeks (23–35weeks) and mean BW of 907g (530–1730g). Risk factors other than GA and BW for ROP, identified in the predictive logistic regression model, were blood transfusion [odds ratio (OR) 1.27] and diagnosis with intraventricular hemorrhage (OR=2.90). Strabismus was identified in 14% of the study cohort. Diagnosis of hyperopia (spherical equivalent ⩾+0.75D) was equal in both ROP and no-ROP groups (p=0.56). Myopia (spherical equivalent ⩾−0.75D) and astigmatism ⩾1.00D were diagnosed more frequently in the ROP group (p<0.0001 and 0.04, respectively).ConclusionsA higher incidence of ROP was observed in this cohort compared to some Saudi Arabian centers. It is recommended that the screening criteria be maintained and that the effects of further control of blood transfusion be assessed in a prospective study. The authors recommend an extra ophthalmic evaluation at the age of 18–24months for all premature infants born with GA⩽32weeks

An extremely rare complete bilateral duplication of Inferior vena cava in a male cadaver: anatomy, embryology and clinical relevance

The study presented an extremely rare case of real complete bilateral duplication of inferior vena cava (IVC) in a male cadaver which has never been reported before. Both IVC had approximately the same diameter. The right IVC drained into the right atrium; the left IVC continued as hemiazygos vein and drained into the superior vena cava. Three anastomotic venous channels, a cranial preaortic, a middle and a caudal retroaortic, joined both vessels. Multiple variations in the way of drainage of posterior intercostal veins, on both sides, were also present. The present report invalidates an old classification defining the two vessels when joined at the level of the renal veins as complete bilateral duplication of IVC. Although the presence of combination of venous variations is extremely rare, awareness of such variations is essential for clinical and surgical procedures to avoid misdiagnosis and surgical complications