They propose a joint model for 1) identifying event keywords in a text, 2) identifying entities, and 3) identifying the connections between these events and entities. They also do this across different sentences, jointly for the whole text.

https://i.imgur.com/ETKZL7V.png

Example of the entity and event annotation that the system is modelling.

The entity detection part is done with a CRF; the structure of an event is learned with a probabilistic graphical model; information is integrated from surrounding sentences using a Stanford coreference system; and these are all tied together across the whole document using Integer Linear Programming.