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COMPUTATIONAL GEOMETRY-THEORY AND APPLICATIONS 2025年 129卷

作者： Depian, Thomas Noellenburg, Martin Terziadis, Soeren Wallinger, Markus TU Wien Algorithms & Complex Grp Vienna Austria TU Eindhoven Algorithms Cluster Eindhoven Netherlands Tech Univ Munich Chair Efficient Algorithms Munich Germany

Boundary labeling is a technique in computational geometry used to label sets of features in an illustration. It involves placing labels along an axis-parallel bounding box and connecting each label with its corresponding feature using non-crossing leader lines. Although boundary labeling is well-studied, semantic constraints on the labels have not been investigated thoroughly. In this paper, we introduce grouping and ordering constraints in boundary labeling: Grouping constraints enforce that all labels in a group are placed consecutively on the boundary, and ordering constraints enforce a partial order over the labels. We show that it is NP-hard to find a labeling for arbitrarily sized labels with unrestricted positions along one side of the boundary. However, we obtain polynomialtime algorithms if we restrict this problem either to uniform-height labels or to a finite set of candidate positions. Furthermore, we show that finding a labeling on two opposite sides of the boundary is NP-complete, even for uniform-height labels and finite label positions. Finally, we experimentally confirm that our approach has also practical relevance. (c) 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://***/licenses/by/4.0/).

关键词： Boundary labeling Grouping constraints Ordering constraints Dynamic programming Computational complexity

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Constrained Boundary Labeling 35

Constrained Boundary Labeling

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35th International Symposium on algorithms and Computation, ISAAC 2024

作者： Depian, Thomas Nöllenburg, Martin Terziadis, Soeren Wallinger, Markus Algorithms and Complexity Group TU Wien Austria Algorithms cluster TU Eindhoven Netherlands Technical University of Munich Germany

ISBN: (纸本)9783959773546

Boundary labeling is a technique in computational geometry used to label dense sets of feature points in an illustration. It involves placing labels along an axis-aligned bounding box and connecting each label with its corresponding feature point using non-crossing leader lines. Although boundary labeling is well-studied, semantic constraints on the labels have not been investigated thoroughly. In this paper, we introduce grouping and ordering constraints in boundary labeling: Grouping constraints enforce that all labels in a group are placed consecutively on the boundary, and ordering constraints enforce a partial order over the labels. We show that it is NP-hard to find a labeling for arbitrarily sized labels with unrestricted positions along one side of the boundary. However, we obtain polynomial-time algorithms if we restrict this problem either to uniform-height labels or to a finite set of candidate positions. Finally, we show that finding a labeling on two opposite sides of the boundary is NP-complete, even for uniform-height labels and finite label positions. © Thomas Depian, Martin Nöllenburg, Soeren Terziadis, and Markus Wallinger.

关键词： Computational geometry

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Synthesis of regular expression problems and solutions

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International Journal of Computers and Applications 2020年第8期42卷 748-764页

作者： Ade-Ibijola, Abejide Formal Structures Algorithms and Industrial Applications Research Cluster School of Consumer Intelligence and Information Systems University of Johannesburg Johannesburg South Africa

Formal languages and automata (FLA) theory is perceived by many as one of the hardest topics to teach or learn at the undergraduate level, due to the abstract nature of its contents;often containing proofs, lots of symbolic notations, and specifications of abstract computing machines that are difficult for many students to relate with. One way of approaching this problem is to administer numerous practice problems to students to aid learning. In this paper, we present: definitions of formal rules (using context-free grammar notations) for the synthesis of practice problems and solutions in a sub-domain of formal language theory–regular expressions, new algorithms for implementing these rules with iterations of generated problem instances and associated solutions. Generated problems are then embedded in predefined, short text response and multiple-choice question templates. The implementation of this technique produced numerous problems and solutions that can be used as practice, test or examination questions to support the teaching of regular expressions as a topic in FLA at the undergraduate level. © 2018 Informa UK Limited, trading as Taylor & Francis Group.

关键词： Context free grammars

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Toward industrial C8 production: oxygen intrusion drives renewable n-caprylate production from ethanol and acetate via intermediate metabolite production

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GREEN CHEMISTRY 2025年第11期27卷 2931-2949页

作者： Gemeinhardt, Kurt Jeon, Byoung Seung Ntihuga, Jean Nepomuscene Wang, Han Schlaiss, Caroline Lucas, Timo N. Bessarab, Irina Nalpas, Nicolas Zhou, Nanqing Usack, Joseph G. Huson, Daniel H. Williams, Rohan B. H. Macek, Boris Aristilde, Ludmilla Angenent, Largus T. Univ Tubingen Dept Geosci Schnarrenbergstr 94-96 D-72076 Tubingen Germany Korea Inst Ceram Engn & Technol Ctr Convergence Bioceram Mat 202 Osongsaengmyeong 1 Ro Osong 28160 Chungbuk South Korea Max Planck Inst Biol AG Angenent Max Planck Ring 5 D-72076 Tubingen Germany Univ Tubingen Dept Comp Sci Algorithms Bioinformat Sand 14 D-72076 Tubingen Germany Natl Univ Singapore Ctr Life Sci Singapore Ctr Environm Life Sci Engn 28 Med Dr Singapore 117456 Singapore Univ Tubingen Proteome Ctr Tubingen Morgenstelle 15 D-72076 Tubingen Germany Northwestern Univ Dept Civil & Environm Engn 2145 Sheridan Rd Evanston IL 60208 USA Univ Georgia Dept Food Sci & Technol 100 Cedar St Athens GA 30602 USA Aarhus Univ Dept Biol & Chem Engn Gustav Wieds Vej 10D DK-8000 Aarhus Denmark Aarhus Univ Novo Nord Fdn Res Ctr CORC CO2 Gustav Wieds Vej 10C DK-8000 Aarhus Denmark Univ Tubingen Cluster Excellence Tubingen Germany

Previous bioreactor studies achieved high volumetric n-caprylate (i.e., n-octanoate) production rates and selectivities from ethanol and acetate with chain-elongating microbiomes. However, the metabolic pathways from the substrates to n-caprylate synthesis were unclear. We operated two n-caprylate-producing upflow bioreactors with a synthetic medium to study the underlying metabolic pathways. The operating period exceeded 2.5 years, with a peak volumetric n-caprylate production rate of 190 +/- 8.4 mmol C L-1 d-1 (0.14 g L-1 h-1). We identified oxygen availability as a critical performance parameter, facilitating intermediate metabolite production from ethanol. Bottle experiments in the presence and absence of oxygen with 13C-labeled ethanol suggest acetyl-coenzyme A-based derived production of n-butyrate (i.e., n-butanoate), n-caproate (i.e., n-hexanoate), and n-caprylate. Here, we postulate a trophic hierarchy within the bioreactor microbiomes based on metagenomics, metaproteomics, and metabolomics data, as well as experiments with a Clostridium kluyveri isolate. First, the aerobic bacterium Pseudoclavibacter caeni and the facultative anaerobic fungus Cyberlindnera jadinii converted part of the ethanol pool into the intermediate metabolites succinate, lactate, and pyroglutamate. Second, the strict anaerobic C. kluyveri elongated acetate with the residual ethanol to n-butyrate. Third, Caproicibacter fermentans and Oscillibacter valericigenes elongated n-butyrate with the intermediate metabolites to n-caproate and then to n-caprylate. Among the carbon chain-elongating pathways of carboxylates, the tricarboxylic acid cycle and the reverse beta-oxidation pathways showed a positive correlation with n-caprylate production. The results of this study inspire the realization of a chain-elongating production platform with separately controlled aerobic and anaerobic stages to produce n-caprylate renewably as an attractive chemical from ethanol and acetate as substrates.

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Python-Bot: A Chatbot for Teaching Python Programming

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ENGINEERING LETTERS 2021年第1期29卷 25-34页

作者： Okonkwo, Chinedu Wilfred Ade-Ibijola, Abejide Univ Johannesburg Res Cluster Formal Struct Algorithms & Ind Applic Dept Appl Informat Syst Sch Consumer Intelligence & Informat Syst Johannesburg South Africa

The applications of Artificial Intelligence (AI) in Education is growing continuously. One of the recent AI applications introduced to Education is the Chatbot technology, used to support teaching and administrative tasks. A long standing problem in Computer Science Education (CSE) is how to improve program comprehension for novice programmers. So far, CSE has not seen any Chatbot for supporting the teaching of programming. This paper proposed a Chatbot named Python-Bot that helps novice programmers to understand Python's basic syntactic structures and semantics. Python-Bot was implemented on an existing Chatbot API (called SnatchBot) and an evaluation was performed to prove the effectiveness of Python-Bot. The results suggest that Python-Bot can support novice programmers in the comprehension of programs written in Python. Python-Bot can be found at: https://***/pythonbotchatbot2020.

关键词： Chatbot Python Programming Novice Programmers Computer Science Education Program Comprehension SnatchBot

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GPCR NaVa database:: Natural variants in human G protein-coupled receptors

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HUMAN MUTATION 2008年第1期29卷 39-44页

作者： Kazius, Jeroen Wurdinger, Kerstin van Iterson, Maarten Kok, Joost Back, Thomas Ijzerman, Ad P. Leiden Univ Leiden Amsterdam Ctr Drug Res Div Med Chem NL-2300 RA Leiden Netherlands Leiden Univ Leiden Inst Adv Comp Sci Algorithms Cluster NL-2300 RA Leiden Netherlands

The superfamily of human G protein,coupled receptors (GPCRs) is large and regulates a plethora of important physiological processes by transducing extracellular signals over cell membranes. A diversity of natural variants occurs in these receptors, including rare mutations and common polymorphisms. These variants differ in their impact on DNA, ranging from single nucleotide polymorphisms (SNPs) to copy number variants, and in their impact on protein function. Natural variants furthermore vary in their effects on human phenotypes from neutral to disease-associated. As mutation data are highly dispersed over numerous sources, a single resource for variants would aid investigators of GPCRs. The GPCR NaVa database therefore integrates data on natural variants in human GPCRs from online databases, the scientific literature, and patents.' Where available, variants contain information on their location in the DNA (and protein sequence), the involved nucleotides (and amino acids), the average frequency of each allele, reported disease associations, and references to public databases and the scientific literature. The GPCR NaVa database aims to facilitate studies into pharmacogenetics, genotype-phenotype, and structure-function relationships of GPCRs. The GPCR NaVa database is interlinked with the family-specific GPCRDB resource and is accessible as a stand-alone database through a user-friendly website at http://*** (last accessed 28 August 2007).

关键词： SNP bioinformatics database drug targets G protein-coupled receptors GPCR seven transmembrane receptor 7TM membrane proteins

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Trend Analysis: A Decision Tool in SA Healthcare

Trend Analysis: A Decision Tool in SA Healthcare

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2019 International Multidisciplinary Information Technology and Engineering Conference, IMITEC 2019

作者： Abbott, Simon G Ade-Ibijola, Abejide Formal Structures Algorithms and Industrial Applications Research Cluster School of Consumer Intelligence and Information Systems University of Johannesburg Department of Applied Information Systems South Africa

ISBN: (纸本)9781728100401

The use of medical surveillance and predictive analysis is now more readily available through the intelligent use of modern technology with the use of software tools. Google Trends (GT) is an internet research tool initially utilised for the surveillance of the occurrence of influenza (Flu) internet search trends. Within the last 20 years the internet has become integral to health surveillance by reducing the time to the actual recognition of a disease outbreak, or the detection of a disease trend. GT primarily focused on detecting an outbreak of various strains of the Flu infecting different regions, sporadically or endemically, by monitoring the internet user seeking such medical information. It is currently utilised as an adjunct to the traditional surveillance tools used in traditional modern medicine. In this paper we have attempted to apply such search criteria using GT within a typical healthcare scenario or disease trend. We focused on the most common diseases found within the South African healthcare environment and presented the results accordingly. The results were found to be aligned to the results of traditional medical surveillance tools. The GT results presented in this paper may have similar applications in other areas of medicine and disease monitoring efforts in South Africa whereby the general population can derive meaningful insights of such disease trends. In addition there is a distinct awareness of this research tool, where many users are utilising the tool for healthcare searches which is becoming more evident in the medical literature. © 2019 IEEE.

关键词： Search engines

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Lecturer's Apprentice: A Chatbot for Assisting Novice Programmers

Lecturer's Apprentice: A Chatbot for Assisting Novice Progra...

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2019 International Multidisciplinary Information Technology and Engineering Conference, IMITEC 2019

作者： Ismail, Mohammed Ade-Ibijola, Abejide Formal Structures Algorithms and Industrial Applications Research Cluster School of Consumer Intelligence and Information Systems University of Johannesburg Department of Applied Information Systems Johannesburg South Africa

ISBN: (纸本)9781728100401

Students often struggle to communicate with their peers or lecturers about some of the issues they face during their time at university, either it be academic or personal. One of these issues is introductory programming, in instances were they choose to memorise code in order to pass rather than understanding how the logic behind the code actually works. Programming requires an understanding of how a certain logical flows and algorithm work. In this article, we discuss the difficulties that students face in introductory programming. We have also developed an interactive AI chatbot tool that students can interact with on some of the academic issues they may face. They can ask for advice on how to understand algorithms and what measures to take in order to understand programming logic and visualise metal models of the algorithms. The chatbot can also be used for personal advice. A survey that was conducted showed that there is a need for such a tool in aiding students through their university life. © 2019 IEEE.

关键词： Students

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A Metric for Estimating the Difficulty of Programming Problems by Ranking the Constructs in their Solutions

A Metric for Estimating the Difficulty of Programming Proble...

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2019 International Multidisciplinary Information Technology and Engineering Conference, IMITEC 2019

作者： Kalemba, Elsa Ade-Ibijola, Abejide Formal Structures Algorithms and Industrial Applications Research Cluster School of Consumer Intelligence and Information Systems University of Johannesburg Department of Applied Information Systems Johannesburg South Africa

ISBN: (纸本)9781728100401

Several studies have been conducted on the complexity of computer programs. Metrics of quantifying computer programs based on programming language, lines of code, or number of modules have been studied. One open problem is: how to measure the complexity of computer programming problems, based on the constructs in their solutions. In this paper, we present a tool called NOPCE (The NOvice Program Complexity Estimator) that measures the complexity of programming problems based on the constructs they contain. NOPCE takes any given novice program written in C# and computes an aggregated weight based on a look-up table of predefined weights for programming constructs. We have presented an evaluation that compares the human perception of problem complexity with that of NOPCE. Results show that, humans agreed with NOPCE on problem ranking, most of the time. This tool may find applications in computer education, where difficulty balancing of programming problems is paramount. © 2019 IEEE.

关键词： Table lookup

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Multicriteria Optimization for Dynamic Demers cartograms

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2022年第6期28卷 2376-2387页

作者： Nickel, Soeren Sondag, Max Meulemans, Wouter Kobourov, Stephen Peltonen, Jaakko Noellenburg, Martin TU Wien A-1040 Vienna Austria TU Wien Algorithms & Complex Grp A-1040 Vienna Austria Swansea Univ Swansea SA2 8PP W Glam Wales TU Eindhoven Algorithms Geometry & Applicat Cluster NL-5612 AZ Eindhoven Netherlands Univ Arizona Dept Comp Sci Tucson AZ 85721 USA Tampere Univ Fac Informat Technol & Commun Sci Stat & Data Anal Tampere 33100 Finland

Cartograms are popular for visualizing numerical data for administrative regions in thematic maps. When there are multiple data values per region (over time or from different datasets) shown as animated or juxtaposed cartograms, preserving the viewer's mental map in terms of stability between multiple cartograms is another important criterion alongside traditional cartogram criteria such as maintaining adjacencies. We present a method to compute stable stable Demers cartograms, where each region is shown as a square scaled proportionally to the given numerical data and similar data yield similar cartograms. We enforce orthogonal separation constraints using linear programming, and measure quality in terms of keeping adjacent regions close (cartogram quality) and using similar positions for a region between the different data values (stability). Our method guarantees the ability to connect most lost adjacencies with minimal-length planar orthogonal polylines. Experiments show that our method yields good quality and stability on multiple quality criteria.

关键词： Time-varying data cartograms mental map preservation

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