Graph Crimes of the Temporal Kind: How LoReTTA Quietly Breaks Time
A fraud model does not only learn from transactions. It learns from sequence. Who interacted with whom. When. How often. After what previous event. Before which next event. In temporal graph systems, the order is not metadata. It is the thing being modelled. That is why LoReTTA is an uncomfortable paper.1 It does not argue that Temporal Graph Neural Networks can be broken only by a powerful adversary with model access, expensive surrogate training, and a theatrical pile of fake edges. It argues something more operationally annoying: a continuous-time graph can be poisoned by removing influential interactions and replacing them with plausible ones. The resulting history still looks enough like history. The model quietly learns the wrong temporal structure. Very civilised, as crimes go. ...