8. A method of determining a hybrid text summary by a hybrid summarization system having a processor, a relevance score determination module, a structural representation of the discourse determination module and a percolation module, the method comprising: determining discourse constituents for a text by the processor; determining a structural representation of discourse for the text by the structural representation of the discourse determination module; determining relevance scores for discourse constituents by the relevance score determination module; percolating relevance scores by the percolation module based on the structural representation of discourse comprising: for each discourse constituent leaf node, determining the number of subordinated edges plus one; determining a score based on the inverse of the number of subordinated edges +1; for each discourse constituent node, assigning the score of a child discourse constituent node to the parent discourse constituent node, if the score is less relevant; for any subordination discourse constituent node, assigning the score of the subordinated discourse constituent node to the subordinating discourse constituent node if the subordinated discourse constituent score is lower; assigning the relevance scores of any coordination discourse constituent node to each child discourse constituent of the coordination if it is lower; determining an adjusted relevance score based on the score and the subordination level; and determining a hybrid text summary, by the processor, based on discourse constituents with relevance scores compared to a threshold relevance score.
8. A method of determining a hybrid text summary by a hybrid summarization system having a processor, a relevance score determination module, a structural representation of the discourse determination module and a percolation module, the method comprising: determining discourse constituents for a text by the processor; determining a structural representation of discourse for the text by the structural representation of the discourse determination module; determining relevance scores for discourse constituents by the relevance score determination module; percolating relevance scores by the percolation module based on the structural representation of discourse comprising: for each discourse constituent leaf node, determining the number of subordinated edges plus one; determining a score based on the inverse of the number of subordinated edges +1; for each discourse constituent node, assigning the score of a child discourse constituent node to the parent discourse constituent node, if the score is less relevant; for any subordination discourse constituent node, assigning the score of the subordinated discourse constituent node to the subordinating discourse constituent node if the subordinated discourse constituent score is lower; assigning the relevance scores of any coordination discourse constituent node to each child discourse constituent of the coordination if it is lower; determining an adjusted relevance score based on the score and the subordination level; and determining a hybrid text summary, by the processor, based on discourse constituents with relevance scores compared to a threshold relevance score. 9. The method of claim 8 , further comprising the steps of: determining a combined relevance score based on the relevance scores and non-structural relevance scores and percolating the combined relevance score.