Chatbots are used in many applications, e.g., automated agents, smart home assistants, interactive characters in online games, etc. Therefore, it is crucial to ensure they do not behave in undesired manners, providing offensive or toxic responses to users. This is not a trivial task as state-of-the-art chatbot models are trained on large, public datasets openly collected from the Internet. This paper presents a first-of-its-kind, large-scale measurement of toxicity in chatbots. We show that publicly available chatbots are prone to providing toxic responses when fed toxic queries. Even more worryingly, some non-toxic queries can trigger toxic responses too. We then set out to design and experiment with an attack, ToxicBuddy, which relies on fine-tuning GPT-2 to generate non-toxic queries that make chatbots respond in a toxic manner. Our extensive experimental evaluation demonstrates that our attack is effective against public chatbot models and outperforms manually-crafted malicious queries proposed by previous work. We also evaluate three defense mechanisms against ToxicBuddy, showing that they either reduce the attack performance at the cost of affecting the chatbot's utility or are only effective at mitigating a portion of the attack. This highlights the need for more research from the computer security and online safety communities to ensure that chatbot models do not hurt their users. Overall, we are confident that ToxicBuddy can be used as an auditing tool and that our work will pave the way toward designing more effective defenses for chatbot safety.@en

The dissemination of hateful memes online has adverse effects on social media platforms and the real world. Detecting hateful memes is challenging, one of the reasons being the evolutionary nature of memes; new hateful memes can emerge by fusing hateful connotations with other cultural ideas or symbols. In this paper, we propose a framework that leverages multimodal contrastive learning models, in particular OpenAI's CLIP, to identify targets of hateful content and systematically investigate the evolution of hateful memes. We find that semantic regularities exist in CLIP-generated embeddings that describe semantic relationships within the same modality (images) or across modalities (images and text). Leveraging this property, we study how hateful memes are created by combining visual elements from multiple images or fusing textual information with a hateful image. We demonstrate the capabilities of our framework for analyzing the evolution of hateful memes by focusing on antisemitic memes, particularly the Happy Merchant meme. Using our framework on a dataset extracted from 4chan, we find 3.3K variants of the Happy Merchant meme, with some linked to specific countries, persons, or organizations. We envision that our framework can be used to aid human moderators by flagging new variants of hateful memes so that moderators can manually verify them and mitigate the problem of hateful content online. @en

“Densification” is an inevitable trend of modern urban development. The blend and apposition of new extension with historical environment would be an important feature of cities in the next age, which would further bring about the discussion and speculation on historical value and contemporaneity. As a typical representative of high-density countries, in the last decade, the Netherlands has performed outstanding in the adaptive transformation of the built environment. Based on the interview with Prof. Kees Kaan, the founder architect of KAAN Architecten, this paper makes an in-depth analysis of the stand and method of Dutch architects facing the complex historical environment. The interview focuses particularly on transformation and renovation strategies, heritage values and practical experience, with a view to obtaining traceable research clues on design involvement in the issues of preservation and renewal.@en

Exhibition in gebouw De Heuvel of Students work of the Msc 1 studio Dutch Change, organised by the Chair of Complex Projects, Faculty of architecture. 29th of April - 1st of May.@en

Exhibition in gebouw De Heuvel of Students work of the Msc 1 studio Dutch Change, organised by the Chair of Complex Projects, Faculty of architecture. 29th of April - 1st of May.@en