7. The system of claim 1 , wherein the one or more numerical values are determined based on the number of text units that contain the first term or the one or more second terms, or the number of occurrences of the first term or the one or more second terms in the text units.
7. The system of claim 1 , wherein the one or more numerical values are determined based on the number of text units that contain the first term or the one or more second terms, or the number of occurrences of the first term or the one or more second terms in the text units. 8. The system of claim 7 , wherein the one or more numerical values are determined further by dividing the one or more numerical values by the total number of text units in the first group.