One of the central problems of algebraic complexity theory is the complexity of multiplication in algebras. For this, first, the concept of algebra is defined and the class of algebras under study is fixed. Then the concept of the algorithm and its complexity are clarified. in the most general sense, an algebra is a set with operations. An operation is defined, as a rule, as a function of one or more elements of a set, the set of values of which is the original set or some of its subset. Usually, a set of elementary operations is fixed, for example, a Boolean operation on two bits, addition or multiplication of two numbers, after which a computation model is fixed, for example, a sequential algorithm, at each step of which one elementary o...