2. The system of claim 1 , wherein the operations comprise commutative operations and non-commutative operations, wherein the seed structure has inputs adapted to receive contributions and wherein the seed structure is adapted to apply commutative operations to the contributions received on each input and to apply commutative or non-commutative operations to the results of the commutative operations applied to said contributions.
2. The system of claim 1 , wherein the operations comprise commutative operations and non-commutative operations, wherein the seed structure has inputs adapted to receive contributions and wherein the seed structure is adapted to apply commutative operations to the contributions received on each input and to apply commutative or non-commutative operations to the results of the commutative operations applied to said contributions. 16. The system of claim 2 , wherein a terminal alphabet of the context free grammar comprises at least a solid, union, intersection and subtraction.