The tertiary opposition is not sufficient to characterize all types of syn­tactic relations. And though Hjelmslev claims that there may be only three types of relations between two elements, the claim is correct only in the sphere of logic. Language material proves that, here, the situation is more complicated, and logical relations are not able to cover all the diversity of syntactic relations within grammatically organized structures.

Although syntactic studies are replete with the term “relation”, this no­tion is rarely explained and specified. Without going into philosophical im­plications, “relation” may be defined, in syntactic analysis, as “mutual de­pendence of elements” which may (or may not) be expressed formally. Any relation is objective and as real as the elements between which it appears.

For example, if we distinguish such a word combination as the girl a let­ter from the larger construction to write the girl a letter, the nouns girl and letter appear to be interdependent and, consequently, mutually related. The relation between them may be proved by means of replacement that causes changes of the form: (to write) the girl a letter – (to write) a letter to the girl. The relations between these nouns may not be identified with the help of the types distinguished within syntax. The two nouns do not reveal any relations of equitable elements and may not be joined by any co-ordinate conjunc­tion, i.e. they do not show co-ordination. It is hardly possible to claim that one of these elements is the head and the other depends on it, which proves absence of subordinate relations. The relations within the word combination are not those of interdependence, since each of the two nouns may function without the other – to write a letter, to write to the girl. This operation is impossible for interdependent elements.

As the relations of the type are not very distinct and groups, linked in such a way, may be identified as syntactic structures only if we bear in mind the element outside the word combination in question, this type of relations may be termed accumulative in order to show its amorphous properties.

Accumulative relations are observed not only in groups of two objects of different types. Accumulative relations are widely spread in attribu­tive groups that consist of attributes expressed by different morphological classes (e.g. these suede shoes, some famous authors). The examples above contain elements that are not indifferent to each other, since their syntactic position is fixed and they may not change places: *‘suede these shoes, *fa-mous some authors.

The fixed position proves that the elements in a given attributive group are linked by a certain types of relation. The relation is not that of co-ordina­tion, since the elements may not be joined by any co-ordinate conjunction. The relations of subordination and interdependence between the components are not revealed either, as none of the attributes dominates the other and the elements may function without each other: these shoes — suede shoes; some authors -famous authors. Thus, we have the grounds to claim that the at­tributive group is based on accumulation.

In Slavonic linguistics, these constructions are usually classified as at­tributive groups with heterogeneous subordination. This term defines the relation of attributive elements to a unit outside the group without qualify­ing the relation between the elements within an attributive group. In at­tributive groups with homogeneous subordination (e.g. beautiful blue eyes; cold windy evening), however, the relations between attributes are classified as co-ordinate. In other words, in cases of homogeneous subordination of pre-positional attributes, both external (homogeneous subordination) and internal (co-ordination) relations are distinguished. Unlike these structures, heterogeneous subordination defines only the type of relations between the modified word and the modifier, without specifying relations between the modifiers. Introducing the notion accumulative relation fills in the gap.

As a result, at this stage, our classification includes the four types of syntactic relation: interdependence – co-ordination – subordination – accu­mulation.