5. A computer-implemented method for text processing, comprising: processing one or more semantic constructs comprising semantic elements; recognizing respective syntactic roles of the semantic elements, wherein syntactic roles of the different semantic elements are represented by a given sentence as a hierarchical structure such as a tree, having subordinate and superordinate branches connected at nodes; representing the semantic constructs by respective hierarchical data structures, which represent hierarchical relationships among the semantic elements of the respective semantic constructs; removing at least one selected semantic element from the hierarchical data structures, so as to produce respective nuclear data structures; aggregating similar nuclear constructs, so that frequently occurring nuclear constructs are given high statistical significance; invoking an action with respect to the nuclear data structures; and computing respective occurrence frequencies of the nuclear data structures, wherein invoking the action comprises invoking the action with respect to one or more of the nuclear data structures whose occurrence frequencies meet a predefined condition, wherein removing the at least one selected semantic element comprises predefining a nuclearization depth, and determining the selected semantic elements to be removed responsively to the predefined nuclearization depth.
5. A computer-implemented method for text processing, comprising: processing one or more semantic constructs comprising semantic elements; recognizing respective syntactic roles of the semantic elements, wherein syntactic roles of the different semantic elements are represented by a given sentence as a hierarchical structure such as a tree, having subordinate and superordinate branches connected at nodes; representing the semantic constructs by respective hierarchical data structures, which represent hierarchical relationships among the semantic elements of the respective semantic constructs; removing at least one selected semantic element from the hierarchical data structures, so as to produce respective nuclear data structures; aggregating similar nuclear constructs, so that frequently occurring nuclear constructs are given high statistical significance; invoking an action with respect to the nuclear data structures; and computing respective occurrence frequencies of the nuclear data structures, wherein invoking the action comprises invoking the action with respect to one or more of the nuclear data structures whose occurrence frequencies meet a predefined condition, wherein removing the at least one selected semantic element comprises predefining a nuclearization depth, and determining the selected semantic elements to be removed responsively to the predefined nuclearization depth. 6. The method according to claim 5 , wherein the semantic constructs comprise transcribed audio of call center sessions.