Rankings play a crucial role in various contexts but often exhibit incompleteness, top-weightedness, and indefiniteness. Comparing rankings can reveal underlying similarities, yet traditional correlation coefficients like Kendall's tau do not adequately address these complexities. Rank-Biased Overlap (RBO) addresses these challenges by accommodating differences in rank length, appropriately weighting ranks, and minimizing data assumptions. This paper investigates the average Rank-Biased Overlap (RBO) between independent rankings, addressing the need for clearly indicated reference values similar to those of correlation coefficients. Our study explores how the expected RBO changes with varying p-parameters, prefix lengths, and degrees of conjointness between domains.
To facilitate this analysis, an algorithm is developed that performs extensive simulations across different values of p, list and domain sizes. By analyzing the simulation results, trends are provided in the average RBO between independent rankings based on these varying parameters and establish relevant reference values. This study focuses on scenarios where prefixes are of the same length and there are no ties in the rankings.

Rankings are more present in our daily lives than most people realize. Whether you are browsing Netflix and getting movies or shows based on your previous likes or dislikes, or you want to compare search engine results. To use rankings in the field of Computer Science a rank similarity is needed. Rank-Biased Overlap is one of those. It is top-weighted, can be used on uneven rankings, and when only a part of the ranking is known. A well-known problem in rank similarity measures is ties. There have been some ways of dealing with ties proposed since RBO was introduced. These ways have been shown to be promising but they only relate to the seen part. The unseen part of rankings is still a new concept with little research done about it. This paper aims to change that a bit. First, a full explanation is given of the three variations of dealing with ties. Then using these variants we show how the assumption that no ties exist in the unseen part affects these variants. Also, the current extrapolation method is researched as there is also a big influence of the above-mentioned assumption. We then use simulated data to give a clear data visualization to show how the theory relates to practice. We have tried to be clear and concise with our explanations and data visualizations so future researchers can use this paper to improve and progress RBO in the world of rank similarity measures.

Rank-biased Overlap (RBO) is a measure that is used to compare two rankings against each other mathematically using a hyperparameter for persistence, p, to define the importance of items higher up in the rankings. This is able to follow the properties of incompleteness, indefiniteness, and top-heaviness for its results, making it a flexible option for rank similarity. In traditional RBO, the intersection of the items in each of the rankings is weighted by the persistence to reach the final value for RBO as it tends towards infinity. RBO has several assumptions, such as on what happens when rankings are tied, having an infinitely long ranking, and a degree of conjointness between the rankings. In this paper, two new variations are derived on the aspects of having the rankings be fully conjoint, as well as the aspect of having a known finite domain for the rankings. These are described through the equations of RBOc, for fully conjoint rankings, and RBOf , for rankings within a known finite domain. While RBOc tends to be slightly larger and RBOf tends to be smaller when compared to traditional RBO, both can be more fitting depending on the greater context of their use cases.

Reducing the similarity of two ranked lists to a single value proves to be useful in various fields of research and industry, such as Information Retrieval and Recommender Systems, leading to the introduction of several similarity measures. One such measure is Rank-Biased Overlap and its variants, possessing qualities such as the ability to handle incomplete rankings, non-conjoint ranking domains and the graceful evaluation of ranking pairs with tied items.
Comparing the performance of similarity measures, or comparing variants of a single measure, requires the presence of ranking data. In certain cases, generating synthetic ranking data may be a more viable option than using real data. However, a review of existing literature reveals a lack of parametrisable synthetic ranking algorithms. This paper introduces a novel method to generate a pair of rankings where one can tailor the conjointness of ranking domains, influence the ranking overlap as a function of depth and tune the presence of tie groups in a probabilistic manner. The paper demonstrates the output of the algorithm when varying the input parameters, verifying the methods performance empirically and statistically.

As a point estimate of the similarity score between two possibly indefinite rankings, extrapolated rank-biased overlap (RBOEXT) uses the assumption that the agreement observed at the last evaluation depth continues indefinitely across the unseen tails of the two lists. This assumption does not account for any patterns that occur in the visible prefixes, imposing a strict restriction on the extrapolation. In an effort to improve the accuracy of RBOEXT, three reformulations with a relaxed theoretical basis are proposed in this paper: one continually re-uses the agreement from the previous depth while the other two rely on regression to fit a function on the seen agreements. Using synthetic data, the performance of these new extrapolation methods is compared to the original's in terms of closeness to the true RBO score as well as the average distance between assumed and actual agreement in the rankings' unseen tails. Overall, an impactful difference is observed in the estimates of agreement generated by the four approaches: as the trends from the visible prefixes are barely captured by the simpler techniques or closely-reproduced by the more flexible ones, the trade-off between under- and overfitting becomes increasingly relevant. The results thus indicate a need for some middle-ground to be established such that it factors in the observed patterns while also generalizing well for the tails.

The phenomenon of one element moving and progressively overlaying another is common in nature, such as waves swashing and backwashing, or eyelids moving over eyeballs while blinking. Folding Texture, which was proposed by Thorben, can simulate this texture “folding” visual effect in real-time without changing geometry.
However, to date, no tool has been developed to assist in the design and synthesis of folding textures. Applications of the technique so far are achieved through manual creation of the folding texture, which is a tedious process.
This thesis explores the problem of folding-texture design and synthesis. A novel approach is proposed for animating still images based on the folding texture technique. The approach uses a semi-automatic, user-assisted method that combines texture editing, motion profile specification, and folding texture synthesis into one seamless process, reducing the need for extensive manual work. It enables novice users to utilize the technique with a fair level of prior knowledge of folding texture.

Meetings are the keystone of a good company. They allow for quick decision making, multiple-perspective problem solving and effective communication. However, most employees and managers have a negative view on the efficiency and quality of their meetings. High quality meetings where every participant feels equally heard and respected is crucial for having positive meeting sentiment within a company. One of the most influential aspects of meetings are speech overlaps. Overlaps range from short utterances such as backchannels, to follow up questions and clarifications, to complete interruptions. In non-competitive cases, the overlapped speaker feels that the other participants are listening and actively engaging with them during the meeting. In competitive cases, the overlapped speaker can feel interrupted and unimportant. Therefore, competitive overlaps often have a negative impact on the course of the discussion and the overlappee's meeting sentiment. In problematic cases, these overlaps should be reduced to a minimum. In order to do this, overlaps must be classified as either competitive or non-competitive. This paper proposes a novel approach to overlap classification, namely that of text-based classification through Large Language Models. Four different prompt designs are used and tested on the two best performing and publicly available models, GPT-3.5-turbo and GPT-4. The results show that the in-context learning approach using the GPT-4 model results in the most accurate classifications. When comparing the results to previous work, it is observed that the text-based GPT-4 model matches carefully engineered neural networks that even adopt a multi-modular approach.

Large Language Models (LLM) have brought significant performance increase on many Natural Language Processing tasks. However LLMs have not been tested for meeting summarization. This research paper examines the effectiveness of the gpt-3.5-turbo model on the meeting summarization domain. However due to input length limitations, it cannot be applied directly to this task. Thus the paper investigates two segmentation methods: a simple context-length window approach and topic segmentation using Latent Dirichlet Allocation (LDA). The context-length window approach's performance is close to the Pointer Generator framework. The topic segmentation gives worse results. Overall gpt-3.5-turbo performs worse with both approaches than state-of-the-art models which use a transformer architecture adapted for long documents.

In April 2020, a Dutch research team swiftly analyzed public opinions on COVID-19 lockdown relaxations. However, due to time constraints, only a small amount of opinion data could be processed. With the surge of popularity in the field of Natural Language Processing (NLP) and the arrival of tools like ChatGPT, a number of tasks involving Large Language Models (LLMs) have become easier. This study aims to address the effectiveness of these LLMs on stance detection using this COVID-19 opinion corpus. The corpus is chunked and sampled to be used as input for OpenAI's GPT-3.5-Turbo LLM. The machine-generated stances are then evaluated against multiple binary classification metrics. It is shown that these models perform very well in the field of stance detection, with an average F-score of 0.895. However, a significant number of misclassifications are observed in one dataset. Therefore we conclude that while LLMs offer valuable guidelines, it is still crucial to verify their outputs when dealing with complex or important public matters.

This paper presents a novel approach to detect agreement and disagreement moments between participants in meeting transcripts without relying on labeled data. We propose a model in which disagreement detection is defined as the process of first identifying argumentative theses relevant to a given corpus of text and then classifying all phrases in the text as being either in favor of, against or expressing no opinion on a given thesis. To identify relevant theses, we compare the performance of a latent Dirichlet allocation-based topic model against that of a diverse set of large language models. To classify the stance of a phrase with respect to a thesis, only large language models are used. We find that, while state-of-the-art large language models do not outperform topic modeling-based approaches in extracting semantically relevant content, they are capable of presenting such content in a more concise and grammatically correct manner. We also find that state-of-the-art large language models are not capable of accurately performing stance classification as described above.

Inductive Program Synthesis (IPS) has been implemented by a two-stage search algorithm, Brute, and consequently improved upon with a Large Neighborhood Search (LNS) technique, in an algorithm named Vlute. Unmotivated values and design choices within Vlute caused limitations on the performance of IPS tasks. This research improves upon several of these limitations through experiments. Most significant improvements are found in the robot-planning domain through the implementation of a stochastic accept method and a best improvement neighbor search.

This paper addresses the problem of Inductive Synthesis by analysing the Metropolis-Hastings stochastic search algorithm. The goal of Inductive Synthesis is to generate programs whose intended behaviour is established through the use of input and output examples. The Metropolis-Hastings algorithm searches the set of all possible programs and finds possible solutions. Our experiments show that while optimization can be done under certain conditions, it does not improve the
algorithm’s success rate in synthesizing programs on complex domains compared to more randomized but domainspecific approaches.

A recent development in program synthesis is using Monte Carlo Tree Search to traverse the search tree of possible programs in order to efficiently find a program that will successfully transform the given input to the desired output. Previous research has shown promising results as Monte Carlo Tree Search is able to escape local optima that occur during the search. I have continued this previous research by changing some components of Monte
Carlo Tree Search and testing them on three different domains; robot planning, string transformations and ASCII art.
Most notable, I have found that by changing the exploration constant Cp to slowly decrease during the running of the algorithm, you can improve the algorithm’s accuracy. This makes it easier for the algorithm to escape local optima, however here it is crucial the parameters are tuned well. Furthermore, I have also found that improvements can still be made in the expansion step of MCTS. However, changes to which values are backpropagated have not shown an improvement in the accuracy of MCTS in program synthesis.

VanillaGP is an Inductive Program Synthesis algorithm that takes a Genetic Algorithm (GA) approach by using its 3 components: selection, mutation, and crossover. Many different alternatives exist for these components and although this is not the only application of a GAs on the Program Synthesis domain, it has not been extensively evaluated what the effects of using these different alternatives or combinations of them are. We explored this by evaluating the performance of multiple alternatives per component and comparing the results of combinations of these alternatives to VanillaGP. These evaluations were done on 3 IPS domains: robot, ASCII art, and strings. From these evaluations we conclude that Stochastic Universal Sampling combined with Queen Bee Crossover and an altered version of One Mutation Per Solution performs best on the string domain, and Down-Sampled Lexicase Selection combined with Three Parent Crossover and the same altered version of OMPS performs best on the other domains.

P4 programmable data-planes provide operators with a flexible method to set up data-plane forwarding logic. To deploy networks with confidence, a switch's forwarding logic should correspond with its intended behavior. Programs loaded onto programmable data-planes don't necessarily go through as much testing as traditional fixed-function devices from large manufacturers. Security is therefore of utmost importance.

The main question this research attempts to answer, is whether a single compromised P4 switch can corrupt the entire (P4) network. In this scenario the attacker already has access to the compromised switch, and the assumption is made that all devices blindly trust each other. Two load balancing schemes are investigated, Clove-ECN and HULA. The former performs load balancing on the hosts, and results show that switches can transparently influence traffic flow by manipulating the ECN bits. The latter is designed for implementation on the data-plane, e.g. using P4, and we can conclude that HULA is susceptible to attacks by spoofing probe packets with false data.

DDoS attacks are becoming more common and sophisticated. Only recently, in 2017, Google claims they have mitigated an attack which sent 2.54 Tbps of traffic to their servers. In order to prevent these attacks, more and more robust defence mechanisms need to be put in place to withstand the malicious traffic and secure the networks. Programmable data planes allow the users to specify which rules the headers of a packet need to follow and what happens if they are different. With this freedom, achieving more secure networks becomes possible. The use of the programming language P4 makes it easy to modify the functionality of the switches and limit the behaviour of the network in order to reduce the attack surface.
This paper describes certain attacks and mitigation techniques for them, such as DoS attacks and SYN-flood attacks. The paper will list existing defence techniques and enumerate their advantages and drawbacks. There will be two proof of concept detection and mitigation techniques in P4, and these implementations will be compared to already existing ones. The P4 implementations will be provided as well as comparison and performance graphs.

In software defined networking a controller can control where the data-plane routes packets to. Programmable data-planes make networks even more flexible, as the algorithms on the data-plane can be updated. The P4 programming language can be used to program data-planes, and the P4Runtime data-plane API can be used for controller to data-plane communication. The possibility of man-in-the-middle attacks when using P4Runtime was investigated. Man-in-the-middle attacks are possible either between the controller and data-plane, or between two hosts on the network. A virtual network in Mininet was used to try and demonstrate the difference between secure and insecure channels in these two scenarios. A malicious controller can take control of a switch in order to use it for man-in-the-middle attacks when the P4Runtime channel is insecure, but not in a secure channel. The man-in-the-middle attack between the controller and switch was not achieved due to the switches in Mininet only running on localhost and not being able to run the controller in-band. It was concluded that it is indeed recommended to only use secure P4Runtime channels, and possible extensions to this research could be to attempt the same experiment using a different setup or to research the effects that a successful man-in-the-middle attack can have.

Data planes are responsible for forwarding packets in a network. The P4 language is used for programming programmable data planes. Such data planes give more flexibility to programmers by allowing them to define how the packets should be processed. However, these data planes might also be more vulnerable to malicious attacks than traditional (non-programmable) data planes. That is because software is usually more prone to errors as compared to the hardware. Different research has already analyzed various aspects of the security of the P4 language. However, the security vulnerabilities of P4 programs have not been researched in depth. The main contribution of this paper is providing examples of attacks on P4 programs by using manipulated packet data. In this research, it was attempted to corrupt three P4 programs by manipulating packet data. Two of the three attempts were successful. The paper concludes that some P4 programs can be corrupted by malicious packets.

After software defined networking (SDN) separated the control-plane from the dataplane, P4 was proposed as a solution to be able to program the data-plane. The programmable data plane (PDP) is very useful to alter the behaviour of programmable network devices. The drawback, however, is that without virtualization only one single P4 program can run at a time on the PDP. Compiler based and hypervisor based approaches can be used to virtualize the P4 data-plane to let P4 programs run alongside each other. This increases the flexibility when compared to P4, but can potentially come with added risks. Hypervisor based approaches share resources, while compiler based approaches try to minimize the sharing of resources. This opens up hypervisor based approaches, like HyperVDP and Hyper4, to attacks from a corrupt P4 program. Because of the resource sharing, when one of the virtualized P4 programs in HyperVDP is corrupted, there potentially is a risk that the other virtualized programs also get influenced. This paper will attempt to answer the question; can a malicious P4 program corrupt behaviour of another P4 program while running alongside each other. This will be done by laying out a method to answer this question using HyperVDP. A repository containing the updated source code of HyperVDP will also be created and provided to allow for a stable framework.