In mathematics, a quadratic algebra is a filtered algebra generated by degree one elements, with defining relations of degree 2. It was pointed out by Yuri Manin that such algebras play an important role in the theory of quantum groups. The most important class of graded quadratic algebras is Koszul algebras.
Yuri Manin knows how to multiply
If you are doing algebra you have to know basic math first.  
( z1 know :ARG0 ( z2 person :name ( z3 name :op "Yuri" :op "Manin" ) ) :ARG1 ( z4 multiply :ARG0 z2 ) )