Sergei Vladimirovich Protopopov (Russian: Серге́й Владимирович Протопопов; 2 April [O.S.
Due to the ideological incompatibility of avant-garde with the contemporary regime supporting socialist realism, his works were mostly unknown following 1931.
Both in his compositions and in his teaching, Protopopov was a strong supporter of Yavorsky's theories of modal rhythm and tritone.
Technically, they are very demanding for the interpreter, as well as for the instrument—they employ full standard range of piano, sometimes going even beyond that.
The piano sonatas are often notated in three staves, and for simplicity accidentals take effect only at the given note.