Anton Karazeev on classical methods of keyphrases extraction from (biomedical) texts: statistical (TF-IDF) and graphical (TextRank).
Besides them, newly proposed methods were discussed: based on Information Theory (Kullback-Leibler divergence) using word2gauss algorithm.
- [2015, ICLR] Word Representations via Gaussian Embedding
-  Multimodal Word Distributions
-  EmbedRank: Unsupervised Keyphrase Extraction using Sentence Embeddings
-  Keyword Extraction Using Word Co-occurrence