Calculating space

[D Sceviour]

Toga II 3.0 gives a non-linear bonus for pieces on enemy half of the board (the more the better).

I have using an approach similar to the Toga approach mentioned for some time. If I take it out, then the program plays weaker. This is an indication that "space" value is primary and crucial to the total evaluation. That is, space is one of the four corner stones of chess being: material, space, time and pawn structure. You cannot simply adjust a space value. I think space has to be considered first and then other values adjusted around it. Of course, this is only my conclusion but it seems to be supported by a number of chess authors. Still, if I am wrong then tell me how to remove a space calculation without damaging the search.