The renowned mathematician, Paul Erdős, has published more than 1500 papers in various branches of mathematics including discrete mathematics, graph theory, number theory, mathematical analysis, approximation theory, set theory, and probability theory. A complete list of his published works is available in an [archive organized by Jerrold Grossman][1]. 

But besides the published papers, it is quite likely for a very active mathematician like Erdős to have a long list of unpublished/unfinished papers as well. Just like a treasure trove, these notes may contain incredibly valuable mathematical stuff such as conjectures, lemmas, proof ideas, etc., which can easily be expanded to full papers or at least give rise to some interesting research ideas as a source of inspiration. 

> **Question.** Is any repository of (even a portion of) Erdős' unpublished/unfinished works available? If yes, is it publicly and freely accessible on/offline? I am particularly interested in those unpublished works of him which are related to set theory and infinitary combinatorics.       


  [1]: https://oakland.edu/enp/pubinfo/