A taxonomy for emergency service station location problem

The emergency service station (ESS) location problem has been widely studied in the literature since 1970s. There has been a growing interest in the subject especially after 1990s. Various models with different objective functions and constraints have been proposed in the academic literature and efficient solution techniques have been developed to provide good solutions in reasonable times. However, there is not any study that systematically classifies different problem types and methodologies to address them. This paper presents a taxonomic framework for the ESS location problem using an operations research perspective. In this framework, we basically consider the type of the emergency, the objective function, constraints, model assumptions, modeling, and solution techniques. We also analyze a variety of papers related to the literature in order to demonstrate the effectiveness of the taxonomy and to get insights for possible research directions

Approximating Subdense Instances of Covering Problems

We study approximability of subdense instances of various covering problems on graphs, defined as instances in which the minimum or average degree is Omega(n/psi(n)) for some function psi(n)=omega(1) of the instance size. We design new approximation algorithms as well as new polynomial time approximation schemes (PTASs) for those problems and establish first approximation hardness results for them. Interestingly, in some cases we were able to prove optimality of the underlying approximation ratios, under usual complexity-theoretic assumptions. Our results for the Vertex Cover problem depend on an improved recursive sampling method which could be of independent interest

PEMODELAN SET COVERING PROBLEM DALAM PENENTUAN LOKASI HALTE BUS RAPID TRANSIT (BRT) PADA KORIDOR RAJABASA-SUKARAJA DI KOTA BANDAR LAMPUNG

Bandar Lampung merupakan kota besar di Indonesia yang akan berkembang menjadi kota metropolitan. Perkembangan kota dapat dipercepat dengan pembangunan infrastruktur pelayanan publik. Pengembangan transportasi umum seperti Bus Rapid Transit (BRT) di Kota Bandar Lampung diharapkan dapat meningkatkan ketertarikan masyarakat untuk menggunakan transportasi umum sehingga dapat menekan penggunaan kendaraan pribadi untuk mengurangi tingkat kemacetan dan kecelakaan lalu lintas. Pengoperasian BRT memerlukan adanya fasilitas penunjang, seperti halte. Pembangunan halte yang kurang baik mengakibatkan bertambahnya permasalahan transportasi. Masyarakat sebagai target pengguna menjadi enggan untuk menggunakan BRT karena  kesulitan saat akan memanfaatkan fasilitas tersebut. Tujuan penelitian ini adalah menentukan jumlah dan lokasi halte BRT di sepanjang rute Rajabasa-Sukaraja di Kota Bandar Lampung sehingga dapat memberikan akses yang layak ke halte terdekat kepada semua penumpang dengan jumlah halte yang minimum, tetapi dapat memenuhi semua titik permintaan di sepanjang rute (coverage area). Penentuan lokasi dan jumlah halte di sepanjang rute I BRT dilakukan dengan mengidentifikasi lokasi bangkitan yang mempunyai tingkat permintaan relatif tinggi dan kandidat lokasi halte yang memenuhi kriteria. Lokasi halte terpilih ditentukan dengan metode Set Covering Problem. Hasil perhitungan menyimpulkan terdapat 19 lokasi halte terpilih di sepanjang rute. Dalam penelitian ini juga dilakukan analisis penentuan lokasi halte ketika pemerintah memiliki keterbatasan anggaran pembangunan halte

On the average-case complexity of pattern matching with wildcards

Pattern matching with wildcards is a string matching problem with the goal of finding all factors of a text $t$ of length $n$ that match a pattern $x$ of length $m$, where wildcards (characters that match everything) may be present. In this paper we present a number of complexity results and fast average-case algorithms for pattern matching where wildcards are allowed in the pattern, however, the results are easily adapted to the case where wildcards are allowed in the text as well. We analyse the \textit{average-case} complexity of these algorithms and derive non-trivial time bounds. These are the first results on the average-case complexity of pattern matching with wildcards which provide a provable separation in time complexity between exact pattern matching and pattern matching with wildcards. We introduce the \textit{wc-period} of a string which is the period of the binary mask $x_b$ where $x_b[i]=a$ \textit{iff} $x[i]\neq \phi$ and $b$ otherwise. We denote the length of the wc-period of a string $x$ by \textsc{wcp}(x). We show the following results for constant $0< \epsilon < 1$ and a pattern $x$ of length $m$ and $g$ wildcards with \textsc{wcp}(x)=p the prefix of length $p$ contains $g_p$ wildcards: \begin{itemize} \item If $\displaystyle\lim_{m \rightarrow \infty} \frac{g_p}{p}=0$ there is an optimal algorithm running in \cO(\frac{n \log_\sigma m}{m})-time on average. \item If $\displaystyle\lim_{m \rightarrow \infty} \frac{g_p}{p}=1-\epsilon$ there is an algorithm running in \cO(\frac{n \log_\sigma m\log_2 p}{m})-time on average. \item If $\displaystyle\lim_{m \rightarrow \infty} \frac{g}{m} = \displaystyle\lim_{m \rightarrow \infty} 1-f(m)=1$ any algorithm takes at least $\Omega(\frac{n \log_\sigma m}{f(m)})$-time on average. \end{itemize

Система з підтримки процесу верифікації програмного продукту

Магістерська дисертація: 91 с., 23 рис., 7 табл., 37 джерел, 1 додаток. Актуальність. Розробка якісного програмного продукту - це складний процес, який вимагає високого рівня підготовки команди розробників. Задля підвищення якості та роботоспроможності програмних продуктів потрібно велику увагу приділяти тестуванню. Ручне тестування в деяких випадках займає більше часу для перевірки системи, в той час як автоматизоване тестування дозволяє значно заощадити витрати компанії-клієнта, зекономити ресурси та час на тестування та підтримку високоякісної продукції та зменшити ризик випуску неякісних продуктів або продуктів, які не відповідаюсь потребам замовника. Ось чому технологія автоматизації тестування дуже популярна серед компаній, що займаються інформаційними технологіями, робота яких пов’язана з розробкою програмного забезпечення. Зв'язок роботи з науковими програмами, планами, темами. Робота виконувалась на кафедрі автоматизованих систем обробки інформації та управління Національного технічного університету України «Київський політехнічний інститут ім. Ігоря Сікорського» в рамках теми «Ефективні методи розв'язання задач теорії розкладів» (№ ДР 0117U000919). Мета дослідження - підвищення якості та надійності програмного продукту за рахунок автоматизації процесу тестуванння, що дозволяє скоротити час та витрати на виконання процесів тестування. Для досягнення мети необхідно виконати наступні завдання: проаналізувати існуючі методи автоматизації тестування програмного забезпечення; провести аналіз відомих робіт з розв’язання поставленої в рамках роботи задачі; розробити методи побудови плану тестування в залежності від обраної стратегії; розробити метаевристичні алгоритми покриття множини для вирішення задачі побудови плану тестування; виконати програмну реалізацію розроблених алгоритмів; налагодити інтеграцію з TeamCity; проаналізувати дані обчислювальних експериментів для визначення параметрів алгоритмів; провести порівняльний аналіз розроблених алгоритмів обраної стратегії. Об’єкт дослідження – процес тестування програмних продуктів. Предмет дослідження – методи автоматизації верифікації програмних продуктів на основі побудови планів тестування програмних продуктів. Наукова новизна одержаних результатів полягає у впровадженні системи для підтримки автоматизованого тестування, яка потребує мінімального втручання людини для знаходження помилок та невідповідностей у роботі програмних продуктів. Публікації. Матеріали роботи опубліковані у збірнику IX Міжнародної науково-практичної конференції “DYNAMICS OF THE DEVELOPMENT OF WORLD SCIENCE” 13-15 травня 2020 у Ванкувері та у тезах всеукраїнської науково-практичної конференції молодих вчених та студентів «Інформаційні системи та технології управління» НТУУ «КПІ ім. Ігоря Сікорського» 26-27 листопада 2020 р .Topicality. Developing a quality software product is a complex process that requires a high level of training from the development team. In order to improve the quality and performance of software products, great attention should be paid to testing. Manual testing in some cases takes more time to test the system, while automated testing can significantly reduce the cost of customer companies, save resources and time used to test and maintain high product quality, and reduce the risk of marketing a substandard product. or a product that does not meet the needs of users. That is why testing automation technologies are quite popular in information technology companies, whose work is related to software development. Relationship of work with scientific programs, plans, themes. The work was performed at the Department of Computer-Aided Management And Data Processing Systems of the National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute» within the topic «Effective methods for solving problems of schedule theory» (state registration number 0117U000919) The purpose of the study is to improve the quality and reliability of the software product by automating the testing process, which reduces the time and cost of testing. To achieve this goal you need to perform the following tasks: to analyze existing methods for software testing automation; to analyze the known work to solve the problem set in the work; to develop methods for building a testing plan depending on the chosen strategy; to develop metaheuristic algorithms for covering the set to solve the problem of constructing a test plan; to perform software implementation of the developed algorithms; to establish integration with TeamCity; to analyze the data of computational experiments to determine the parameters of algorithms; to carry out the comparative analysis of the developed algorithms of the chosen strategy. Object of research is the process of software testing. Subject of research is methods of automation of verification on the basis of construction of plans of testing of software products. The scientific novelty of the obtained results is the introduction of a system to support automated testing, which requires minimal human intervention to find errors and inconsistencies in the operation of software products

Approximation Complexity of Optimization Problems : Structural Foundations and Steiner Tree Problems

In this thesis we study the approximation complexity of the Steiner Tree Problem and related problems as well as foundations in structural complexity theory. The Steiner Tree Problem is one of the most fundamental problems in combinatorial optimization. It asks for a shortest connection of a given set of points in an edge-weighted graph. This problem and its numerous variants have applications ranging from electrical engineering, VLSI design and transportation networks to internet routing. It is closely connected to the famous Traveling Salesman Problem and serves as a benchmark problem for approximation algorithms. We give a survey on the Steiner tree Problem, obtaining lower bounds for approximability of the (1,2)-Steiner Tree Problem by combining hardness results of Berman and Karpinski with reduction methods of Bern and Plassmann. We present approximation algorithms for the Steiner Forest Problem in graphs and bounded hypergraphs, the Prize Collecting Steiner Tree Problem and related problems where prizes are given for pairs of terminals. These results are based on the Primal-Dual method and the Local Ratio framework of Bar-Yehuda. We study the Steiner Network Problem and obtain combinatorial approximation algorithms with reasonable running time for two special cases, namely the Uniform Uncapacitated Case and the Prize Collecting Uniform Uncapacitated Case. For the general case, Jain's algorithms obtains an approximation ratio of 2, based on the Ellipsoid Method. We obtain polynomial time approximation schemes for the Dense Prize Collecting Steiner Tree Problem, Dense k-Steiner Problem and the Dense Class Steiner Tree Problem based on the methods of Karpinski and Zelikovsky for approximating the Dense Steiner Tree Problem. Motivated by the question which parameters make the Steiner Tree problem hard to solve, we make an excurs into Fixed Parameter Complexity, focussing on structural aspects of the W-Hierarchy. We prove a Speedup Theorem for the classes FPT and SP and versions if Levin's Lower Bound Theorem for the class SP as well as for Randomized Space Complexity. Starting from the approximation schemes for the dense Steiner Tree problems, we deal with the efficiency of polynomial time approximation schemes in general. We separate the class EPTAS from PTAS under some reasonable complexity theoretic assumption. The same separation was achieved by Cesaty and Trevisan under some assumtion from Fixed Parameter Complexity. We construct an oracle under which our assumtion holds but that of Cesati and Trevisan does not, which implies that using relativizing proof techniques one cannot show that our assumption implies theirs

On Approximability of Bounded Degree Instances of Selected Optimization Problems

In order to cope with the approximation hardness of an underlying optimization problem, it is advantageous to consider specific families of instances with properties that can be exploited to obtain efficient approximation algorithms for the restricted version of the problem with improved performance guarantees. In this thesis, we investigate the approximation complexity of selected NP-hard optimization problems restricted to instances with bounded degree, occurrence or weight parameter. Specifically, we consider the family of dense instances, where typically the average degree is bounded from below by some function of the size of the instance. Complementarily, we examine the family of sparse instances, in which the average degree is bounded from above by some fixed constant. We focus on developing new methods for proving explicit approximation hardness results for general as well as for restricted instances. The fist part of the thesis contributes to the systematic investigation of the VERTEX COVER problem in k-hypergraphs and k-partite k-hypergraphs with density and regularity constraints. We design efficient approximation algorithms for the problems with improved performance guarantees as compared to the general case. On the other hand, we prove the optimality of our approximation upper bounds under the Unique Games Conjecture or a variant. In the second part of the thesis, we study mainly the approximation hardness of restricted instances of selected global optimization problems. We establish improved or in some cases the first inapproximability thresholds for the problems considered in this thesis such as the METRIC DIMENSION problem restricted to graphs with maximum degree 3 and the (1,2)-STEINER TREE problem. We introduce a new reductions method for proving explicit approximation lower bounds for problems that are related to the TRAVELING SALESPERSON (TSP) problem. In particular, we prove the best up to now inapproximability thresholds for the general METRIC TSP problem, the ASYMMETRIC TSP problem, the SHORTEST SUPERSTRING problem, the MAXIMUM TSP problem and TSP problems with bounded metrics