1. A computer implemented database system having data structures for storing, in a memory, data and information defining relations between the data, comprising: a first data structure, stored in the memory, having a definition of at least one data set wherein each data set includes a data set identifier and logically holds data objects of the same type; a second data structure, stored in the memory, having definitions of properties of objects wherein each property includes an identifier of the property and an identifier of a set, from the first data structure, the property is assigned to; a third data structure, stored in the memory, having definitions of objects wherein each object includes an identifier and an identifier of a set, from the first data structure, the object is assigned to; a fourth data structure, stored in the memory, having definitions of properties of each object wherein each property of an object associates a value with an object, from the third data structure, and a property of the set, from the second data structure, the object is assigned to; a fifth data structure, stored in the memory, having definitions of relations wherein each relation includes an identifier of the relation; and a sixth data structure, stored in the memory, for storing definitions of relations between objects wherein each objects relation associates a relation, from the fifth data structure, to two objects from the third data structure.