Grammar as a phenomenon – a subsystem of language as a linguistic discipline

Grammatical category
is a generalized gram. meaning realized through formal and meaningful opposition of variants of one and the same unit.
Any gram. category is represented by at min. 2 categorial forms. Otherway it does not exist because a grammatical category is a representation of a general meaning
var. its particular manifestations.
The method of opposition
The opposition (in the linguistic sense) may be defined as a generalised correlation of lingual forms by means of which a certain function is expressed. The correlated elements (members) of the opposition must possess two types of features: common features and differential features. Common features serve as the basis of contrast, while differential features immediately express the function in question.

Trubetskoy -> Smirnitskiy

Partially similar elements (i.e. means elements having common and distinctive features) constitute an opposition, the members of which differ in form and meaning :
Dog-dogs Common – plane of expression, number
Diff. – in form and meaning of quantity
The oppositional theory was originally formulated as a ; phonological theory. Three main qualitative types of oppositions were established in phonology: "privative", "gradual", and "equipollent". By the number of members contrasted, oppositions were divided into binary (two members) and more than binary (ternary, quaternary, etc.).


Types of oppositions
(1)According to the number (2) qualitatively:
of members (elements) opposed

• 
  binary – 2 members -privative ex. ask⁻ - asked⁺(binary)
  
• 
  tertiary – 3 members -equipollent ex. am⁺ - is⁺(binary)
  
• 
  quaternary – 4 members (both elem are marked)
  

-gradual- gradation- only in ->degrees of comparison (ex. good – better-the best - tertiary)

*(объяснение,чтоб было понятно)The most important type of opposition is the binary privative opposition; the other types of oppositions are reducible to the binary privative opposition.