In this paper we give definitions of basic concepts such as symmetries, first
integrals, Hamiltonian and recursion operators suitable for ordinary
differential equations on associative algebras, and in particular for matrix
differential equations. We choose existence of hierarchies of first integrals
and/or symmetries as a criterion for integrability and justify it by examples.
Using our componentless approach we have solved a number of classification
problems for integrable equations on free associative algebras. Also, in the
simplest case, we have listed all possible Hamiltonian operators of low order.Comment: 19 pages, LaTe