Hye-Woo Lee, Noo-ri Kim, and Jee-Hyong Lee. Int. J. Fuzzy Log. Intell. Syst. 2017;17:1-9. https://doi.org/10.5391/IJFIS.2017.17.1.1

Session-based recommendation aims to predict the user's next action based on anonymous sessions without using side information. Most of the real-world session datasets are sparse and have long-tail item distribution. Although long-tail item recommendation plays a crucial role in improving user satisfaction, only a few methods have been proposed to take the long-tail session recommendation into consideration. Previous works in handling data sparsity problems are mostly limited to self-supervised learning techniques with heuristic augmentation which can ruin the original characteristic of session datasets, sequential and co-occurrences, and make noisier short sessions by dropping items and cropping sequences. We propose a novel method, LOAM, improving LOng-tail session-based recommendation via niche walk Augmentation and tail session Mixup, that alleviates popularity bias and enhances long-tail recommendation performance. LOAM consists of two modules, Niche Walk Augmentation (NWA) and Tail Session Mixup (TSM). NWA can generate synthetic sessions considering long-tail distribution which are likely to be found in original datasets, unlike previous heuristic methods, and expose a recommender model to various item transitions with global information. This improves the item coverage of recommendations. TSM makes the model more generalized and robust by interpolating sessions at the representation level. It encourages the recommender system to predict niche items with more diversity and relevance. We conduct extensive experiments with four real-world datasets and verify that our methods greatly improve tail performance while balancing overall performance.

Federated learning, a data privacy-focused distributed learning method, trains a model by aggregating local knowledge from clients. Each client collects and utilizes its own local dataset to train a local model. Local models in the connected federated learning network are uploaded to the server. In the server, local models are aggregated into a global model. During the process, no local data is transmitted in or out of any client. This procedure may protect data privacy; however, federated learning has a worse case of example forgetting problem than centralized learning. The problem manifests in lower performance in testing. We propose federated weighted averaging (FedWAvg). FedWAvg identifies forgettable examples in each client and utilizes that information to rebalance local models via weighting. By weighting clients with more forgettable examples, such clients are better represented and global models can acquire more knowledge from normally neglected clients. FedWAvg diminishes the example forgetting problem and achieve better performance. Our experiments on SVHN and CIFAR-10 datasets demonstrate that our proposed method gets improved performance compared to existing federated learning algorithm in non-IID settings, and that our proposed method can palliate the example forgetting problem.

An approach for game bot detection in massively multiplayer online role‐playing games (MMORPGs) based on the analysis of game playing behavior is proposed. Since MMORPGs are large‐scale games, users can play in various ways. This variety in playing behavior makes it hard to detect game bots based on play behaviors. To cope with this problem, the proposed approach observes game playing behaviors of users and groups them by their behavioral similarities. Then, it develops a local bot detection model for each player group. Since the locally optimized models can more accurately detect game bots within each player group, the combination of those models brings about overall improvement. Behavioral features are selected and developed to accurately detect game bots with the low resolution data, considering common aspects of MMORPG playing. Through the experiment with the real data from a game currently in service, it is shown that the proposed local model approach yields more accurate results.

Code summarization is the process of automatically generating brief and informative summaries of source code to aid in software comprehension and maintenance. In this paper, we propose a novel model called READSUM, REtrieval-augmented ADaptive transformer for source code SUMmarization, that combines both abstractive and extractive approaches. Our proposed model generates code summaries in an abstractive manner, taking into account both the structural and sequential information of the input code, while also utilizing an extractive approach that leverages a retrieved summary of similar code to increase the frequency of important keywords. To effectively blend the original code and the retrieved similar code at the embedding layer stage, we obtain the augmented representation of the original code and the retrieved code through multi-head self-attention. In addition, we develop a self-attention network that adaptively learns the structural and sequential information for the representations in the encoder stage. Furthermore, we design a fusion network to capture the relation between the original code and the retrieved summary at the decoder stage. The fusion network effectively guides summary generation based on the retrieved summary. Finally, READSUM extracts important keywords using an extractive approach and generates high-quality summaries using an abstractive approach that considers both the structural and sequential information of the source code. We demonstrate the superiority of READSUM through various experiments and an ablation study. Additionally, we perform a human evaluation to assess the quality of the generated summary.