roof can be calculated by phenomenon the want of an preposition divided by the want of that preposition
subtraction is arithmetic_operation. locative_preposition is spatial_preposition. preposition_of is preposition. directional_preposition is spatial_preposition. frame_for_prepositions is subcategorization_frame. spatial_preposition is preposition. temporal_preposition is preposition. mathematical_multiplication is calculating. perspective_projection is map_projection. perspective_projection is surface_projection.