Relational cost analysis

Programming languages research has made great progress towards statically estimating the execution cost of a program. However, when one is interested in how the execution costs of two programs compare to each other (i.e., relational cost analysis), the use of unary techniques does not work well in many cases. In order to support a relational cost analysis, we must ultimately support reasoning about not only the executions of a single program, but also the executions of two programs, taking into account their similarities. This dissertation makes several contributions to the understanding and development of such a relational cost analysis. It shows how: • Refinement types and effect systems can express functional and relational quantitative properties of pairs of programs, including the difference in execution costs. • Relational cost analysis can be adapted to reason about dynamic stability, a measure of the update times of incremental programs as their inputs change. • A sound and complete bidirectional type system can be developed (and implemented) for relational cost analysis.Die Programmiersprachen-Forschung hat große Fortschritte bei der statischen Einschätzung der Ausführungskosten von Programmen gemacht.Wenn man allerdings wissen möchte, wie die Ausführungskosten zweier Programme sich zueinander verhalten (relationale Kostenanalyse), funktionieren unäre Methoden in vielen Fällen nicht gut. Eine relationale Analyse muss insbesondere nicht nur die Ausführung eines einzelnen Programmes betrachten, sondern die Ausführung beider Programme, um Ähnlichkeiten berücksichtigen zu können. Diese Dissertation liefert mehrere Beiträge zum Verständnis und zur Entwicklung solcher relationalen Kostenanalysen. Sie zeigt: • Refinement-Typsysteme und Effekt-System können funktional und relational qualitative Eigenschaften von Programmpaaren ausdrücken, insbesondere die Differenz der Ausführungskosten. • Relationale Kostenanalyse kann angepasst werden, um dynamische Stabilität zu analysieren. Diese misst die Update-Zeit inkrementeller Programme, wenn deren Eingaben sich ändern. • Ein korrektes und vollständiges bidirektionales Typsystem für die relationale Kostenanalyse kann entwickelt und implementiert werden

Work Analysis with Resource-Aware Session Types

While there exist several successful techniques for supporting programmers in deriving static resource bounds for sequential code, analyzing the resource usage of message-passing concurrent processes poses additional challenges. To meet these challenges, this article presents an analysis for statically deriving worst-case bounds on the total work performed by message-passing processes. To decompose interacting processes into components that can be analyzed in isolation, the analysis is based on novel resource-aware session types, which describe protocols and resource contracts for inter-process communication. A key innovation is that both messages and processes carry potential to share and amortize cost while communicating. To symbolically express resource usage in a setting without static data structures and intrinsic sizes, resource contracts describe bounds that are functions of interactions between processes. Resource-aware session types combine standard binary session types and type-based amortized resource analysis in a linear type system. This type system is formulated for a core session-type calculus of the language SILL and proved sound with respect to a multiset-based operational cost semantics that tracks the total number of messages that are exchanged in a system. The effectiveness of the analysis is demonstrated by analyzing standard examples from amortized analysis and the literature on session types and by a comparative performance analysis of different concurrent programs implementing the same interface.Comment: 25 pages, 2 pages of references, 11 pages of appendix, Accepted at LICS 201

Bidirectional Type Checking for Relational Properties

Relational type systems have been designed for several applications including information flow, differential privacy, and cost analysis. In order to achieve the best results, these systems often use relational refinements and relational effects to maximally exploit the similarity in the structure of the two programs being compared. Relational type systems are appealing for relational properties because they deliver simpler and more precise verification than what could be derived from typing the two programs separately. However, relational type systems do not yet achieve the practical appeal of their non-relational counterpart, in part because of the lack of a general foundations for implementing them. In this paper, we take a step in this direction by developing bidirectional relational type checking for systems with relational refinements and effects. Our approach achieves the benefits of bidirectional type checking, in a relational setting. In particular, it significantly reduces the need for typing annotations through the combination of type checking and type inference. In order to highlight the foundational nature of our approach, we develop bidirectional versions of several relational type systems which incrementally combine many different components needed for expressive relational analysis.Comment: 14 page

Relational Symbolic Execution

Symbolic execution is a classical program analysis technique used to show that programs satisfy or violate given specifications. In this work we generalize symbolic execution to support program analysis for relational specifications in the form of relational properties - these are properties about two runs of two programs on related inputs, or about two executions of a single program on related inputs. Relational properties are useful to formalize notions in security and privacy, and to reason about program optimizations. We design a relational symbolic execution engine, named RelSym which supports interactive refutation, as well as proving of relational properties for programs written in a language with arrays and for-like loops

Is there any differences in magnetic resonance imaging findings of painful temporomandibular joint between patients with and without vertigo?

Background/Aim: Temporomandibular disorder (TMD) is an umbrella term and consists of pathological situations about temporomandibular joint (TMJ) internal structure, masticatory muscle and associated structures. Otalgic complaints are included in the group of complaints within TMJ associated structures and are frequently seen with TMD. The aim of this study is to evaluate the magnetic resonance imaging findings (MRI) of patients who had unilateral pain in the preauricular region, diagnosed with vertigo. Material and Methods: The present retrospective and cross-sectional clinical study was carried out on patients presenting with preauricular pain referred to XXX University Faculty of Dentistry Department of Oral and Maxillofacial Surgery between 2018 and 2020. There were 2 groups as vertigo and health groups. MRI findings were the primary predictor variables, while pain was the primary outcome variable, recorded on a visual analog scale (VAS). Results: 120 patients were included in the study. The patients included in both groups are between 19 and 65 years of age and there is no significant statistical difference between mean ages of the groups (p>0.05). The VAS values varies between 6 and 9 in both groups. There is no significant statistical difference between mean VAS values of the groups (p>0.05). On the painful side there is no significant difference between the groups in terms of disc/condyle relation (p>0.05). On the other hand moderate effusion (61.4%) was significantly higher in the healthy group while severe effusion (54%) was significantly higher in the vertigo group (p<0.01). Conclusions: Although both groups had the same pain scale, it was observed that the vertigo group had more dramatic MRI findings in terms of disc/condyle relation and presence of effusion. This study is the first to evaluate the disc/condyle relation and the presence of effusion through MRI in vertigo patients diagnosed with TMD

Bounded Expectations: Resource Analysis for Probabilistic Programs

This paper presents a new static analysis for deriving upper bounds on the expected resource consumption of probabilistic programs. The analysis is fully automatic and derives symbolic bounds that are multivariate polynomials of the inputs. The new technique combines manual state-of-the-art reasoning techniques for probabilistic programs with an effective method for automatic resource-bound analysis of deterministic programs. It can be seen as both, an extension of automatic amortized resource analysis (AARA) to probabilistic programs and an automation of manual reasoning for probabilistic programs that is based on weakest preconditions. As a result, bound inference can be reduced to off-the-shelf LP solving in many cases and automatically-derived bounds can be interactively extended with standard program logics if the automation fails. Building on existing work, the soundness of the analysis is proved with respect to an operational semantics that is based on Markov decision processes. The effectiveness of the technique is demonstrated with a prototype implementation that is used to automatically analyze 39 challenging probabilistic programs and randomized algorithms. Experimental results indicate that the derived constant factors in the bounds are very precise and even optimal for many programs

The Effect of Long-Term Hearing Aid Use On Speech Discrimination And Device Satisfaction

Bu çalışmada işitme cihazı kullanımının önemine dikkat çekmek ve işitme cihazı kullanımının becerilerinden olan konuşmayı ayırt etme performanslarının etkilenimini, aynı zamanda memnuniyet düzeyini incelemek amaçlanmıştır. Araştırma 01.03.2021-31.08.2021 tarihleri arasında Duyum İşitme Merkezi’nde (Gebze/Kocaeli) muayene edilerek işitme kaybı nedeniyle odyolojik değerlendirme sonucu işitme cihazı önerilen 18-65 yaş arasındaki toplam 50 hastaya ait dosya ve arşiv bilgileri taranarak, yaş, eğitim ve sosyoekonomik düzey farkı gözetilmeksizin çalışma kapsamına alınmıştır. Hastalara ait genel bilgiler hasta dosyalarından ve çalışmanın yapıldığı merkezde cihazlanan hastalara ait arşivlenmiş odyolojik tetkik ve cihazlama formlarından alındı. Hastaların en az 6 aylık işitme cihazı kullanımı sonrasındaki cihazlı ve cihazsız odyolojik değerlendirmeleri yeniden yapıldı. Hastalardan “Uluslararası İşitme Cihazları Değerlendirme Envanteri”ni doldurmaları istendi. Çalışma sonucunda altı aydan uzun süre işitme cihazı kullanımından sonra cihazlı test skorlarında iyileşme olduğu görülmüş olmasına karşın cihazsız test skorlarında iyileşme görülmemiştir. Cihazlamadan altı ay sonraki cihazsız test sonuçları mevcut işitme fonksiyonunun işitme cihazıyla düzeltilemediğini göstermektedir. Cihaz memnuniyeti ile cihazlı konuşmayı ayırt etme düzeyi arasında ilişki bulunmazken cihazlı PTA ve SRT arasında anlamlı bir ilişki saptanması cihaz memnuniyetinin amplifijkasyon ile daha sıkı ilişki içerisinde olduğunu akıllara getirmektedir

Refinement Types for Incremental Computational Complexity

International audienceWith recent advances, programs can be compiled to efficiently respond to incremental input changes. However, there is no language level support for reasoning about the time complexity of incremental updates. Motivated by this gap, we present CostIt, a higher-order functional language with a lightweight refinement type system for proving asymptotic bounds on incremental computation time. Type refinements specify which parts of inputs and outputs may change, as well as dynamic stability, a measure of time required to propagate changes to a program's execution trace, given modified inputs. We prove our type system sound using a new step-indexed cost semantics for change propagation and demonstrate the precision and generality of our technique through examples

Döner Kanat Aerodinamiği ve Hesaplamalı Akışkanlar Dinamiği – Autogyro Tasarım ve Analizleri

Autogyro başarı ile uçan ilk döner kanatlı hava aracıdır. Autogyro’nun motoru pervaneyi kalkış ve düz uçuş sırasında çalıştırmak için kullanılır ve motor uçuş sırasında rotor’a bağlı değildir. Rotor motordan bir güç gereksinimi duymadan aracın ileri hareketi ile kendine doğru gelen hava akışı sayesinde döner. Böylece belli bir dönüş hızına ulaşan rotor, bu hava akışı ile rotor kanatları/palaları üzerine etki eden kuvvetler sayesinde aracın havalanmasına, havada kalmasına ve ileri gitmesine yardımcı olur. Helikopterlerin gelişmesi ile geri planda kalan ve daha çok sportif amaçlı kullanılan autogyrolara bilimsel araştırma anlamında yeterince ilgi gösterilmediğinden literatürde sınırlı sayıda çalışma bulunmaktadır. Günümüzdeki yeni autogyro tasarımlarında daha çok yolcu kapasitesi ile daha hızlı olan ve daha sessiz rotor karakteristiğine sahip yolcu taşıma amaçlı tasarımlara doğru gidilmektedir. Temel döner kanat aerodinamiği teorilerine dayanan tasarım ve performans/aerodinamik analiz yazılım araçlarının geliştirilmesi ve autogyro gereksinimlerine göre kullanılması ve detaylı aerodinamik analizlerinin yapılarak autogyro aerodinamiğinin incelenmesi bu projenin amacıdır