EDBT 2026 Demo / reviewers in the wild / expert
Allan De Freitas
dblp:132/4785
· DBLP profile ↗
15ranked-venue papers in the field
6as first author
4since 2021 · last 2025
0000-0002-8552-481XORCID · corroborated
Domains — venue-derived; a paper can count in several
Other / Interdisciplinary · 15 (6 first)
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2025 | Evaluation of LLM Reasoning Under Uncertainty: An Atomic Comparison to Normative ApproachesabstractEvaluating uncertainty in large language model (LLM) reasoning is challenging due to their vast parameter space, abstract knowledge representation, and limited transparency regarding training data. While normative formalisms, such as deductive logic, clearly define sound reasoning in the absence of uncertainty, reasoning under uncertainty admits multiple approaches, including probabilistic reasoning (e.g. Bayesian), belief function reasoning (e.g. Dempster-Shafer), or fuzzy logic, to name a few. This paper examines how LLMs handle uncertainty by analyzing outcomes based on an atomic fusion and reasoning problem. We establish a point of reference using the simplest of fusion topologies to facilitate transparency and understanding of how LLMs align with established theories. The reasoning approaches of different LLMs with varying complexities are compared to established normative frameworks, providing insights into which formalism best aligns with LLM reasoning and assessing its soundness and consistency. A deviation function for assessment is developed, and the results indicate that the tested LLMs' reasoning under uncertainty does not consistently align with established theories, even for the simplest information fusion topologies. These preliminary results form the basis for further investigations and LLM refinements. J. P. de Villiers, Allan De Freitas, Anne-Laure Jousselme, Lance M. Kaplan, Erik Blasch, Claire Laudy, P. C. Costa |
FUSION | 2 |
| 2023 | Uncertain about ChatGPT: enabling the uncertainty evaluation of large language modelsabstractChatGPT, OpenAI’s chatbot, has gained consider-able attention since its launch in November 2022, owing to its ability to formulate articulated responses to text queries and comments relating to seemingly any conceivable subject. As impressive as the majority of interactions with ChatGPT are, this large language model has a number of acknowledged shortcomings, which in several cases, may be directly related to how ChatGPT handles uncertainty. The objective of this paper is to pave the way to formal analysis of ChatGPT uncertainty handling. To this end, the ability of the Uncertainty Representation and Reasoning Framework (URREF) ontology is assessed, to support such analysis. Elements of structured experiments for reproducible results are identified. The dataset built varies Information Criteria of Correctness, Non-specificity, Self-confidence, Relevance and Inconsistency, and the Source Criteria of Reliability, Competency and Type. ChatGPT’s answers are analyzed along Information Criteria of Correctness, Non-specificity and Self-confidence. Both generic and singular information are sequentially provided. The outcome of this preliminary study is twofold: Firstly, we validate that the experimental setup is efficient in capturing aspects of ChatGPT uncertainty handling. Secondly, we identify possible modifications to the URREF ontology that will be discussed and eventually implemented in URREF ontology Version 4.0 under development. Anne-Laure Jousselme, Johan Pieter de Villiers, Allan De Freitas, Erik Blasch, Valentina Dragos, Gregor Pavlin, Paulo C. G. Costa, Kathryn B. Laskey, Claire Laudy |
FUSION | 3 |
| 2022 | Particle-balanced context-based filtering for hypothesis maintenance in sparse sensor coverage situations
P. Nell, Allan De Freitas, Gregor Pavlin, Johan Pieter de Villiers |
FUSION | 2 |
| 2021 | An embedded platform approach to privacy-centric person re-identification
Nicholas Pym, Allan De Freitas |
FUSION | 2 |
| 2020 | Visual comparison of statistical feature aggregation methods for video-based similarity applicationsabstractVideo data is increasingly being provided by multiple sources. These sources are used to obtain reliable feature information within the context of training data shortages. As such it becomes crucial to interpret and refine such information. Recent research on video content analysis often use deep-learning features due to their outstanding performance in different domains. These features are aggregated over time to create a video-level descriptor. In this research, we explore the potential of statistical feature aggregation methods in combining deep-learning features that represent the visual content of videos. In particular, the contributions of this paper are two-fold: Firstly, we compared statistical feature aggregation methods by selecting movie sequels, calculating their in-sequel-mean-distance and out-of-sequel-mean-distance as well as the Bhattacharyya distance between them and using Principal Component Analysis (PCA) and T-distributed Stochastic Neighbour Embedding (t-SNE) to visualise their distribution in the feature space. This is important to easily comprehend the video content without the need to watch them and understand how well the statistical feature aggregation methods represent the videos. Secondly, the performance of these aggregation methods is explored in the context of a content-based video retrieval task which is evaluated in terms of relevance. The observed results show that the statistical feature aggregation method based on variance outperforms the methods based on maximum, mean, median, median absolute deviation and interquartile range. This outcome is supported when interpreting the t-SNE visualisation method as well as Bhattacharyya distance calculations. Overall statistical feature aggregation methods which measure the spread of a distribution achieve better performance compared to methods that are a measure of location. Adolfo Almeida, Johan Pieter de Villiers, Allan De Freitas, Mergandran Velayudan |
FUSION | 3 |
| 2020 | Dashcam based wildlife detection and classification using fused data sets of digital photographic and simulated imageryabstractIn this paper, data from a simulated data set were fused with a significantly smaller measured data set for the purpose of training a deep neural network to identify animals from the footage of a dash cam. The trained networks were used to detect wildlife in an environment similar to game reserves in South Africa. To enable the automatic collection of data for the experiment, a simulated environment was created to simulate four classes of wildlife found in South Africa: buffalo, elephants, rhino and zebra. The network structure for the detector network selected was an adapted version of the tiny YOLOv3 network. It was discovered that using transfer learning and fine tuning resulted in two models with higher accuracy of 82.59% and 86.64% [email protected] respectively than models where no transfer learning was used. The results were achieved when tested on a testing set of digital photographic images. These networks, initialised using transfer learning, were also faster and easier to train than training using a combined data set of photographic and simulated images from scratch. The simulated environment can however not replace real-life data, as was proven by an accuracy of no better than chance for the model trained using only simulated data. Bianca A. Ferreira, Johan Pieter de Villiers, Allan De Freitas |
FUSION | 3 |
| 2019 | A Maximum Likelihood Approach to Joint Groupwise Image Registration and Fusion by a Student-$t$ Mixture Model
Hao Zhu 0003, Chunxia Tang, Allan De Freitas, Lyudmila Mihaylova |
FUSION | 3 |
| 2019 | Global Optimization for Resource Allocation in a Networked-Surveillance Radar
Allan De Freitas, Richard W. Focke, Conrad Beyers, Johan Pieter de Villiers |
FUSION | 1 |
| 2018 | A Gaussian Process Convolution Particle Filter for Multiple Extended Objects Tracking with Non-Regular ShapesabstractExtended object tracking has become an integral part of various autonomous systems in diverse fields. Although it has been extensively studied over the past decade, many complex challenges remain in the context of extended object tracking. In this paper, a new method for tracking multiple irregularly shaped extended objects using surface measurements is proposed. The Gaussian Process Convolution Particle Filter proposed in [1], designed to track a single extended/group object, is enhanced for tracking multiple extended objects. A convolution kernel is proposed to estimate the multi-object likelihood. A target birth/death model based on the proposed method is also introduced for automatic initiation and deletion of the objects. The proposed approach is validated on real-world LiDAR data which shows that the method is efficient in tracking multiple irregularly shaped extended objects in challenging scenarios involving occlusion, dense clutter and low object detection. Waqas Aftab, Allan De Freitas, Mahnaz Arvaneh, Lyudmila Mihaylova |
FUSION | 2 |
| 2018 | Response Surface Modeling for Networked Radar Resource AllocationabstractSensormanagement is an important function of any data fusion center as the output of a fusion system is dependent on the quality of the information collected. In this paper, the scheduling aspect of sensor management function is implemented using Response Surface Modeling (RSM). Applying RSM requires formulating the sensor management function as an objective function. The benefit of RSM over prior global optimization approaches is the simplification of the evaluation of this objective function to find global optima. This leads to either reduced computational requirements and/ or shorter due times for creating sensor schedules. This work shows the utility of RSM towards scheduling multiple sensors, and seeks to introduce RSM to the sensor management community. It is shown that the RSM scheduler provides a significant improvement towards reducing the number of missed targets in a surveillance radar network. This is compared to performing a uniform scanning regime (or sequential stepped scan) often employed. Very few iterations are required to provide this gain. The RSM technique also quickly determines where the most effective use of sensor resources needs to be applied. Consequently, it spends more radar dwell time on these beam locations. Allan De Freitas, Richard W. Focke, Johan Pieter de Villiers |
FUSION | 1 |
| 2017 | A novel measurement processing approach to the parallel expectation propagation unscented Kalman filterabstractAdvances in sensor systems have resulted in the availability of high resolution sensors, capable of generating massive amounts of data. For complex systems to run online, the primary focus is on computationally efficient filters for the estimation of latent states related to the data. In this paper a novel method for efficient state estimation with the unscented Kalman Filter is proposed. The focus is on applications consisting of a massive amount of data. From a modelling perspective, this amounts to a measurement vector with dimensionality significantly greater than the dimensionality of the state vector. The efficiency of the filter is derived from a parallel filter structure which is enabled by the expectation propagation algorithm. A novel parallel measurement processing expectation propagation unscented Kalman filter is developed. The primary advantage of the novel algorithm is in the ability to achieve computational improvements with negligible loses in filter accuracy. An example of robot localization with a high resolution laser rangefinder sensor is presented. A 47.53% decrease in computational time was exhibited for a scenario with a processing platform consisting of 4 processors, with a negligible loss in accuracy. Allan De Freitas, Carsten Fritsche, Lyudmila Mihaylova, Fredrik Gunnarsson |
FUSION | 1 |
| 2016 | Dealing with massive data with a distributed expectation propagation particle filter for object tracking
Allan De Freitas, Lyudmila Mihaylova |
FUSION | 1 |
| 2015 | How can subsampling reduce complexity in sequential MCMC methods and deal with big data in target tracking?
Allan De Freitas, François Septier, Lyudmila Mihaylova, Simon J. Godsill |
FUSION | 1 |
| 2014 | Crowd tracking with box particle filtering
Nikolay Petrov, Lyudmila Mihaylova, Allan De Freitas, Amadou Gning |
FUSION | 3 |
| 2012 | Multiple scatterer tracking in high range resolution radar
Allan De Freitas, Johan Pieter de Villiers |
FUSION | 1 |