Abstract
<jats:p>The problem of rhythmic characterization of the iambic tetrameter proposed by A. Bely is considered. An algorithm for listing all variants of iambic in quatrain is developed. It is based on the principle of classifying objects introduced in the problems of mathematical linguistics and mathematical biology. Three variants of complete equivalence relations (equality, sameness, congruence) are used as the main classification tool. Equality relation is used to divide the analyzed corpus of stanzas into classes with an equal number of pyrrhics. The sameness relation divides these classes into subclasses of stanzas with the same system of deviations from full stress. The congruence relation compares these subclasses with sets of rhythmic variants called orbits. Due to this, it is possible to enumerate all those possible variants of stanzas that may not be found in a specific set of poems that has been analyzed. To cover the whole variety of rhythmic variants in the poem, A. Bely suggested a special graphic system, which was basically completely correct, but it was in the end criticized by his contemporaries, who, in turn, did not propose anything meaningful in this direction. In this paper, the tool of the necklace problem is used to develop A. Bely's ideas. As a result, not only all the rhythmic figures of 4-st. iambic relate to omissions of stresses listed, but the possibility opens up of eliminating the shortcoming of the graphic method, which consisted in the impossibility of considering the aggravations of unstressed syllables (additional stresses). To do this, it is enough to move from two-color necklaces to three-color ones. In addition, based on the proposed approach, the so-called symmetrical stanzas were identified among the entire corpus of stanzas. It was shown that approximately two thirds of the rhythmic figures proposed by A. Bely correspond to symmetrical stanzas. The methods of the theory of partitions and the theory of linear Diophantine equations were used to enumerate the symmetrical stanzas. The corpus of poems by A. Blok, including the cycles "Poems about the Beautiful Lady" and "Iambics" and individual poems from other cycles was used to analyze all the variants of iambic.</jats:p>