34. The method of claim 26 , wherein the generating of score for a structure having an aggregate comprises calculating a pre-normalized relevance value of a search sub-expression of the search expression for a child of the aggregate, the search sub-expression having a plurality of proximally associated sub-expressions, from previously calculated densities and relevance centers of the proximally associated sub-expressions for children of the aggregate, and from previously calculated pre-normalized relevance values for the individual sub-expressions for the children of the aggregate.
35. The method of claim 34 , wherein the calculating of a pre-normalized relevance value of a search sub-expression of the search expression for a child of the aggregate, comprises calculating 
 ( P+Σ 1≦i≦k W i −Σ 1≦i≦k (Π 1≦j≦m w i,j )) 1/m , where k is a number of children of the aggregate, P is a product of the pre-normalized relevance values of the individual sub-expression for the child, W i is A i *D i /(1+d i ) x , where x is a distance attenuation exponent, A i is a relevance size of the i-th child of the aggregate, D i is a density of the proximally associated sub-expressions in the i-th child of the aggregate, and d i is relevance distance between a relevance center of the child and a relevance center of the proximally associated search sub-expressions in the i-th child of the aggregate; and w i,j is A i *D i,j /(1+d i,j ) x , where x is a distance attenuation exponent, A i is a relevance size of the i-th child of the aggregate, D i,j is a density of the i-th sub-expression in the i-th child of the aggregate, and d i,j is relevance distance between a relevance center of the child and a relevance center of the i-th search sub-expression in the i-th child of the aggregate.