10. A method of determining a word pair relevancy measure for a seed word-keyword pair (d,k), comprising the steps of: identifying a set of documents; identifying search words from the set; pairing a first search word and a second search word to define a search word pair; portioning the set of documents into units; creating a co-occurrence matrix identifying the number of co-occurrences of the search word pair in said units; calculating a conditional co-occurrence probability associated with said search word pair, wherein said conditional co-occurrence probability is based upon said co-occurrence matrix; calculating a transition probability associated with said search word pair, wherein said transition probability is based upon said co-occurrence matrix; and calculating an expected search distance for said seed word-keyword pair, wherein said expected search distance is based upon said conditional co-occurrence probability and said transition probability and wherein said expected search distance is defined as the expected number of units traversed to transition from the seed word to a unit that contains the keyword.
10. A method of determining a word pair relevancy measure for a seed word-keyword pair (d,k), comprising the steps of: identifying a set of documents; identifying search words from the set; pairing a first search word and a second search word to define a search word pair; portioning the set of documents into units; creating a co-occurrence matrix identifying the number of co-occurrences of the search word pair in said units; calculating a conditional co-occurrence probability associated with said search word pair, wherein said conditional co-occurrence probability is based upon said co-occurrence matrix; calculating a transition probability associated with said search word pair, wherein said transition probability is based upon said co-occurrence matrix; and calculating an expected search distance for said seed word-keyword pair, wherein said expected search distance is based upon said conditional co-occurrence probability and said transition probability and wherein said expected search distance is defined as the expected number of units traversed to transition from the seed word to a unit that contains the keyword. 13. The method of claim 10 , wherein said step of calculating a transition probability is provided by: R i , j = C i , j Σ z ⁢ C i , z C j,i represents the value of the co-occurrence matrix associated with the word pair (d i , d j ); and C i,z represents the values of the co-occurrence matrix in row i and column z, associated with the word pair (d i , d z ).