Systems and processes for operating a virtual assistant programmed to refer to shared domain concepts using concept nodes are provided. An example process includes receiving a user speech input, determining a primary domain corresponding to a textual representation of the user speech input, identifying, from the textual representation, a first substring that corresponds to a first concept of the primary domain, parsing the first substring to determine a secondary domain of the plurality of domains, and based on the secondary domain, obtaining a data item corresponding to the first substring. In accordance with determining that the data item is valid for resolving the first concept of the primary domain, extracting, from the data item, a parameter value for the first concept of the primary domain and invoking a service based on the primary domain to produce a result using the parameter value for the first concept.