15. A computer-implemented method comprising: receiving a natural language expression, wherein the natural language expression includes at least one of words, terms, and phrases of text; creating a dialog hypothesis set from the natural language expression by using contextual information, wherein the dialog hypothesis set has a first dialog hypothesis corresponding to a first domain and a second dialog hypothesis corresponding to a second domain; generating, from a first domain engine component and a second domain engine component, a plurality of dialog responses for the dialog hypothesis set; ranking, by machine learning techniques, the first domain engine component and the second domain engine component based on an analysis of the plurality of the dialog responses; and performing an action with the highest ranked domain engine component.
15. A computer-implemented method comprising: receiving a natural language expression, wherein the natural language expression includes at least one of words, terms, and phrases of text; creating a dialog hypothesis set from the natural language expression by using contextual information, wherein the dialog hypothesis set has a first dialog hypothesis corresponding to a first domain and a second dialog hypothesis corresponding to a second domain; generating, from a first domain engine component and a second domain engine component, a plurality of dialog responses for the dialog hypothesis set; ranking, by machine learning techniques, the first domain engine component and the second domain engine component based on an analysis of the plurality of the dialog responses; and performing an action with the highest ranked domain engine component. 19. The computer-implemented method of claim 15 , wherein creating the dialog hypothesis set comprises: extracting at least one feature from the natural language expression; and generating at least two dialog hypotheses, where each dialog hypothesis of the dialog hypothesis set includes a different natural language expression having at least one extracted feature.