Local causal effects with continuous exposures: A matching estimator for the average causal derivative effect

The estimation of causal effects is a fundamental goal in the field of causal inference. However, it is challenging for various reasons. One reason is that the exposure (or treatment) is naturally continuous in many real-world scenarios. When dealing with continuous exposure, dichotomizing the exposure variable based on a pre-defined threshold may result in a biased understanding of causal relationships. In this paper, we propose a novel causal inference framework that can measure the causal effect of continuous exposure. We define the expectation of a derivative of potential outcomes at a specific exposure level as the average causal derivative effect. Additionally, we propose a matching method for this estimator and propose a permutation approach to test the hypothesis of no local causal effect. We also investigate the asymptotic properties of the proposed estimator and examine its performance through simulation studies. Finally, we apply this causal framework in a real data example of Chronic Obstructive Pulmonary Disease (COPD) patients.Comment: 27 pages, 2 figures, 4 tables. Supplementary materials are available. The R files are available at https://github.com/suhwanbong121/average_causal_derivative_effec

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Department of Industrial EngineeringThe development of models for process outcome prediction using event logs has evolved with a clear focus on performance improvement. In this thesis we take a different perspective, focusing on obtaining interpretable predictive models for outcome prediction. In particular, we propose a method based on association rule mining, which results in inherently interpretable classification models. While association rule mining has been used with event logs for process model approximation and anomaly detection in the past, its application to outcome-based predictive model is novel. The proposed method defines how to pre-process logs, obtain the rules, prune the rules to a limited number that can be handled by human decision makers, and use the rules to predict process outcomes. The experimental results on real world event logs show that in most cases the performance of the proposed method is aligned with the one of traditional approaches, with only a slight decrease in some cases. We argue that such a decrease of performance is an acceptable trade-off in return for a predictive model that is interpretable by design.ope

Domain Alignment and Temporal Aggregation for Unsupervised Video Object Segmentation

Unsupervised video object segmentation aims at detecting and segmenting the most salient object in videos. In recent times, two-stream approaches that collaboratively leverage appearance cues and motion cues have attracted extensive attention thanks to their powerful performance. However, there are two limitations faced by those methods: 1) the domain gap between appearance and motion information is not well considered; and 2) long-term temporal coherence within a video sequence is not exploited. To overcome these limitations, we propose a domain alignment module (DAM) and a temporal aggregation module (TAM). DAM resolves the domain gap between two modalities by forcing the values to be in the same range using a cross-correlation mechanism. TAM captures long-term coherence by extracting and leveraging global cues of a video. On public benchmark datasets, our proposed approach demonstrates its effectiveness, outperforming all existing methods by a substantial margin

Tsanet: Temporal and Scale Alignment for Unsupervised Video Object Segmentation

Unsupervised Video Object Segmentation (UVOS) refers to the challenging task of segmenting the prominent object in videos without manual guidance. In recent works, two approaches for UVOS have been discussed that can be divided into: appearance and appearance-motion-based methods, which have limitations respectively. Appearance-based methods do not consider the motion of the target object due to exploiting the correlation information between randomly paired frames. Appearance-motion-based methods have the limitation that the dependency on optical flow is dominant due to fusing the appearance with motion. In this paper, we propose a novel framework for UVOS that can address the aforementioned limitations of the two approaches in terms of both time and scale. Temporal Alignment Fusion aligns the saliency information of adjacent frames with the target frame to leverage the information of adjacent frames. Scale Alignment Decoder predicts the target object mask by aggregating multi-scale feature maps via continuous mapping with implicit neural representation. We present experimental results on public benchmark datasets, DAVIS 2016 and FBMS, which demonstrate the effectiveness of our method. Furthermore, we outperform the state-of-the-art methods on DAVIS 2016.Comment: Accepted to ICIP 202

Treating Motion as Option with Output Selection for Unsupervised Video Object Segmentation

Unsupervised video object segmentation (VOS) is a task that aims to detect the most salient object in a video without external guidance about the object. To leverage the property that salient objects usually have distinctive movements compared to the background, recent methods collaboratively use motion cues extracted from optical flow maps with appearance cues extracted from RGB images. However, as optical flow maps are usually very relevant to segmentation masks, the network is easy to be learned overly dependent on the motion cues during network training. As a result, such two-stream approaches are vulnerable to confusing motion cues, making their prediction unstable. To relieve this issue, we design a novel motion-as-option network by treating motion cues as optional. During network training, RGB images are randomly provided to the motion encoder instead of optical flow maps, to implicitly reduce motion dependency of the network. As the learned motion encoder can deal with both RGB images and optical flow maps, two different predictions can be generated depending on which source information is used as motion input. In order to fully exploit this property, we also propose an adaptive output selection algorithm to adopt optimal prediction result at test time. Our proposed approach affords state-of-the-art performance on all public benchmark datasets, even maintaining real-time inference speed

Global-Local Aggregation with Deformable Point Sampling for Camouflaged Object Detection

The camouflaged object detection (COD) task aims to find and segment objects that have a color or texture that is very similar to that of the background. Despite the difficulties of the task, COD is attracting attention in medical, lifesaving, and anti-military fields. To overcome the difficulties of COD, we propose a novel global-local aggregation architecture with a deformable point sampling method. Further, we propose a global-local aggregation transformer that integrates an object's global information, background, and boundary local information, which is important in COD tasks. The proposed transformer obtains global information from feature channels and effectively extracts important local information from the subdivided patch using the deformable point sampling method. Accordingly, the model effectively integrates global and local information for camouflaged objects and also shows that important boundary information in COD can be efficiently utilized. Our method is evaluated on three popular datasets and achieves state-of-the-art performance. We prove the effectiveness of the proposed method through comparative experiments

Leveraging Spatio-Temporal Dependency for Skeleton-Based Action Recognition

Skeleton-based action recognition has attracted considerable attention due to its compact skeletal structure of the human body. Many recent methods have achieved remarkable performance using graph convolutional networks (GCNs) and convolutional neural networks (CNNs), which extract spatial and temporal features, respectively. Although spatial and temporal dependencies in the human skeleton have been explored, spatio-temporal dependency is rarely considered. In this paper, we propose the Inter-Frame Curve Network (IFC-Net) to effectively leverage the spatio-temporal dependency of the human skeleton. Our proposed network consists of two novel elements: 1) The Inter-Frame Curve (IFC) module; and 2) Dilated Graph Convolution (D-GC). The IFC module increases the spatio-temporal receptive field by identifying meaningful node connections between every adjacent frame and generating spatio-temporal curves based on the identified node connections. The D-GC allows the network to have a large spatial receptive field, which specifically focuses on the spatial domain. The kernels of D-GC are computed from the given adjacency matrices of the graph and reflect large receptive field in a way similar to the dilated CNNs. Our IFC-Net combines these two modules and achieves state-of-the-art performance on three skeleton-based action recognition benchmarks: NTU-RGB+D 60, NTU-RGB+D 120, and Northwestern-UCLA.Comment: 12 pages, 5 figure

Occluded Person Re-Identification via Relational Adaptive Feature Correction Learning

Occluded person re-identification (Re-ID) in images captured by multiple cameras is challenging because the target person is occluded by pedestrians or objects, especially in crowded scenes. In addition to the processes performed during holistic person Re-ID, occluded person Re-ID involves the removal of obstacles and the detection of partially visible body parts. Most existing methods utilize the off-the-shelf pose or parsing networks as pseudo labels, which are prone to error. To address these issues, we propose a novel Occlusion Correction Network (OCNet) that corrects features through relational-weight learning and obtains diverse and representative features without using external networks. In addition, we present a simple concept of a center feature in order to provide an intuitive solution to pedestrian occlusion scenarios. Furthermore, we suggest the idea of Separation Loss (SL) for focusing on different parts between global features and part features. We conduct extensive experiments on five challenging benchmark datasets for occluded and holistic Re-ID tasks to demonstrate that our method achieves superior performance to state-of-the-art methods especially on occluded scene.Comment: ICASSP 202