We consider a scenario where an artificial agent is reading a stream of text composed of a set of narrations, and it is informed about the identity of some of the individuals that are mentioned in the text portion that is currently being read. The agent is expected to learn to follow the narrations, thus disambiguating mentions and discovering new individuals. We focus on the case in which individuals are entities and relations, and we propose an end-to-end trainable memory network that learns to discover and disambiguate them in an online manner, performing oneshot learning, and dealing with a small number of sparse supervisions. Our system builds a not-given-in-advance knowledge base, and it improves its skills while reading unsupervised text. The model deals with abrupt changes in the narration, taking into account their effects when resolving co-references. We showcase the strong disambiguation and discovery skills of our model on a corpus of Wikipedia documents and on a newly introduced dataset, that we make publicly available. * c 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Our work faces the problem of learning to extract information while reading a text stream, with the aim of identifying entities and relations in the text portion that is currently being read. This problem is commonly tackled by assuming the existence of a Knowledge Base (KB) of entities and relations, where several entity/relation instances are paired with additional information, such as the common ways of referring to them or sentences/facts in which they are involved. Then, once an input sentence is provided for reading, sub-portions of text must be linked to entity or relation instances of the KB. The linking process introduces the challenging issue of dealing with multiple distinct entities (relations) that are mentioned with the same text, and thus the system has to disambiguate which is the "right" entity or relation instance of the KB for the considered text fragment. In particular, the context around the fragment or, if needed, information that was provided in the previous sentences of the text stream can be used to perform the disambiguation. As a very simple example, consider the sentence Clyde went to the office, being Clyde and the office two text fragments that indicate entities, while went to is text that is about a relation. Clyde could be the mention that is used to indicate different people in the KB, and several offices could be mentioned by the expression the office (mentions to relations follow the same logic).At a first glance, this problem shares basic principles and intuitions with several existing methods, such as Entity Linking [5], Word Sense Disambiguation [6], Named Entity Recogn...