9. A system, comprising: one or more computer processors; and a memory containing a program, which, when executed by the one or more computer processors, performs an operation comprising: computing a concept score for a first concept in a first case, wherein the concept score is based on whether the first concept is present in at least one of a candidate answer and an item of supporting evidence; adjusting the concept score based on a coefficient for the first concept in a machine learning concept model for the first concept, wherein the coefficient reflects a relevance of the first concept in generating a correct response to the first case; excluding the first concept from consideration when analyzing the candidate answer and the item of supporting evidence to generate a response to the first case upon determining at least one of: (i) that the adjusted concept score does not exceed a predefined minimum weight threshold and (ii) that the coefficient does not exceed a predefined noise threshold; and considering the first concept when analyzing the candidate answer and the item of supporting evidence to generate the response to the first case upon determining at least one of the concept score and the coefficient exceeds a predefined maximum weight threshold.
9. A system, comprising: one or more computer processors; and a memory containing a program, which, when executed by the one or more computer processors, performs an operation comprising: computing a concept score for a first concept in a first case, wherein the concept score is based on whether the first concept is present in at least one of a candidate answer and an item of supporting evidence; adjusting the concept score based on a coefficient for the first concept in a machine learning concept model for the first concept, wherein the coefficient reflects a relevance of the first concept in generating a correct response to the first case; excluding the first concept from consideration when analyzing the candidate answer and the item of supporting evidence to generate a response to the first case upon determining at least one of: (i) that the adjusted concept score does not exceed a predefined minimum weight threshold and (ii) that the coefficient does not exceed a predefined noise threshold; and considering the first concept when analyzing the candidate answer and the item of supporting evidence to generate the response to the first case upon determining at least one of the concept score and the coefficient exceeds a predefined maximum weight threshold. 16. The system of claim 9 , wherein the first concept is stored in an ontology comprising a plurality of concepts and concept relationships.